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Merge branch 'master' into master

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Angelos Chalaris
2017-12-14 20:24:48 +02:00
committed by GitHub
parent 4648bf00c6 be0a582417
commit 5316fcfa0a
27 changed files with 2089 additions and 878 deletions
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21
CONTRIBUTING.md
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@ -7,14 +7,15 @@ Here's what you can do to help:
- [Open issues](https://github.com/Chalarangelo/30-seconds-of-code/issues/new) for things you want to see added or modified.
- Be part of the discussion by helping out with [existing issues](https://github.com/Chalarangelo/30-seconds-of-code/issues) or talking on our [gitter channel](https://gitter.im/30-seconds-of-code/Lobby).
- Submit [pull requests](https://github.com/Chalarangelo/30-seconds-of-code/pulls) with snippets you have created (see below for guidelines).
- Fix typos in existing snippets or run `npm run lint "snippet-name.md"` on unlinted snippets (yes, this is something we actually want help with).
- Tag untagged snippets by running `npm run tagger` and adding the appropriate tag next to the script name in `tag_database`.
- Fix typos in existing snippets or run `npm run linter` to lint unlinted snippets (yes, this is something we actually want help with, as this can take quite a while to run).
### Snippet submission and Pull request guidelines
- **DO NOT MODIFY THE README.md FILE!** Make changes to individual snippet files. You can optionally run `npm run build-list` to update the README.md file automatically, based on the changes you have made.
- **Snippet filenames** must correspond to the title of the snippet. For example if your snippet is titled `### Awesome snippet` the filename should be `awesome-snippet.md`.
- **Snippet filenames** must correspond to the title of the snippet. For example, if your snippet is titled `### Awesome snippet` the filename should be `awesome-snippet.md`.
- Use `kebab-case`, not `snake_case`.
- Avoid capitalization of words, except if the whole word is capitalized (e.g `URL` should be capitalized in the filename and the snippet title).
- Avoid capitalization of words, except if the whole word is capitalized (e.g. `URL` should be capitalized in the filename and the snippet title).
- If there are parentheses in the title, add them to the filename (e.g. `awesome-snippet-(extra-awesome).md` if your snippet's title is `Awesome snippet (extra awesome)`).
- **Snippet titles** should have only the first letter of the first word capitalized. Certain words can be in capitals (e.g. `URL`, `RGB`), but this is on a per-snippet basis.
- All snippet titles must be prefixed with `###` and be at the very first line of your snippet.
@ -28,21 +29,21 @@ Here's what you can do to help:
- Try to keep your snippets' code short and to the point. Use modern techniques and features. Make sure to test your code before submitting.
- All snippets must be followed by one (more if necessary) test case after the code, on a new line, in the form of a comment, along with the expected output. The syntax for this is `myFunction('testInput') -> 'testOutput'`. Use multiline comments only if necessary.
- Try to make your function name unique, so that it does not conflict with existing snippets.
- Snippets should be short (usually below 10 lines). If your snippet is longer than that, you can still submit it and we can help you shorten it or figure out ways to improve it.
- Snippets should be short (usually below 10 lines). If your snippet is longer than that, you can still submit it, and we can help you shorten it or figure out ways to improve it.
- Snippets *should* solve real-world problems, no matter how simple.
- Snippets *should* be abstract enough to be applied to different scenarios.
- It is not mandatory, but highly appreciated if you provide **test cases** and/or performance tests (we recommend using [jsPerf](https://jsperf.com/)).
- It is not mandatory but highly appreciated if you provide **test cases** and/or performance tests (we recommend using [jsPerf](https://jsperf.com/)).
- You can start creating a new snippet, by using the [snippet template](snippet-template.md) to format your snippets.
### Additional guidelines and conventions regarding snippets
- When describing snippets, refer to methods, using their full name. For example, use `Array.reduce()`, instead of `reduce()`.
- If your snippet contains argument with default parameters, explain what happens if they are ommited when calling the function and what the default case is.
- If your snippet contains argument with default parameters, explain what happens if they are omitted when calling the function and what the default case is.
- If your snippet uses recursion, explain the base cases.
- Always use `const functionName` for function definitions.
- Use variables only when necessary. Prefer `const` when the values are not altered after assignment, otherwise use `let`. Avoid using `var`.
- Use variables only when necessary. Prefer `const` when the values are not altered after assignment, otherwise, use `let`. Avoid using `var`.
- Use `camelCase` for function and variable names if they consist of more than one word.
- Try to give meaningful names to variables. For example use `letter`, instead of `lt`. Some exceptions by convention are:
- Try to give meaningful names to variables. For example use `letter`, instead of `lt`. Some exceptions to convention are:
- `arr` for arrays (usually as the snippet function's argument).
- `str` for strings.
- `n` for a numeric value (usually as the snippet function's argument).
@ -54,7 +55,7 @@ Here's what you can do to help:
- `func` for function arguments.
- `nums` for arrays of numbers.
- Use `_` if your function takes no arguments or if an argument inside some function (e.g. `Array.reduce()`) is not used anywhere in your code.
- Specify default parameters for arguments, if necessary. It is preferred to put default parameters last, unless you have pretty good reason not to.
- Specify default parameters for arguments, if necessary. It is preferred to put default parameters last unless you have pretty good reason not to.
- If your snippet's function takes variadic arguments, use `..args` (although in certain cases, it might be needed to use a different name).
- If your snippet function's body is a single statement, omit the `return` keyword and use an expression instead.
- Always use soft tabs (2 spaces), never hard tabs.
@ -72,5 +73,5 @@ Here's what you can do to help:
- Use arrow functions as much as possible, except when you can't.
- Use semicolons whenever necessary. If your snippet function's body is a single statement, return an expression and add a semicolon at the end.
- Leave a single space after a comma (`,`) character.
- Try to strike a balance between readability, brevity and performance.
- Try to strike a balance between readability, brevity, and performance.
- Never use `eval()`. Your snippet will be disqualified immediately.

1522
README.md
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65
package-lock.json generated
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@ -65,16 +65,6 @@
"resolved": "https://registry.npmjs.org/ansi-escapes/-/ansi-escapes-1.4.0.tgz",
"integrity": "sha1-06ioOzGapneTZisT52HHkRQiMG4="
},
"ansi-regex": {
"version": "0.2.1",
"resolved": "https://registry.npmjs.org/ansi-regex/-/ansi-regex-0.2.1.tgz",
"integrity": "sha1-DY6UaWej2BQ/k+JOKYUl/BsiNfk="
},
"ansi-styles": {
"version": "1.1.0",
"resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-1.1.0.tgz",
"integrity": "sha1-6uy/Zs1waIJ2Cy9GkVgrj1XXp94="
},
"anymatch": {
"version": "1.3.2",
"resolved": "https://registry.npmjs.org/anymatch/-/anymatch-1.3.2.tgz",
@ -333,21 +323,39 @@
"integrity": "sha1-Sm+gc5nCa7pH8LJJa00PtAjFVQ0="
},
"chalk": {
"version": "0.5.1",
"resolved": "https://registry.npmjs.org/chalk/-/chalk-0.5.1.tgz",
"integrity": "sha1-Zjs6ZItotV0EaQ1JFnqoN4WPIXQ=",
"version": "2.3.0",
"resolved": "https://registry.npmjs.org/chalk/-/chalk-2.3.0.tgz",
"integrity": "sha512-Az5zJR2CBujap2rqXGaJKaPHyJ0IrUimvYNX+ncCy8PJP4ltOGTrHUIo097ZaL2zMeKYpiCdqDvS6zdrTFok3Q==",
"dev": true,
"requires": {
"ansi-styles": "1.1.0",
"ansi-styles": "3.2.0",
"escape-string-regexp": "1.0.5",
"has-ansi": "0.1.0",
"strip-ansi": "0.3.0",
"supports-color": "0.2.0"
"supports-color": "4.5.0"
},
"dependencies": {
"ansi-styles": {
"version": "3.2.0",
"resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-3.2.0.tgz",
"integrity": "sha512-NnSOmMEYtVR2JVMIGTzynRkkaxtiq1xnFBcdQD/DnNCYPoEPsVJhM98BDyaoNOQIi7p4okdi3E27eN7GQbsUug==",
"dev": true,
"requires": {
"color-convert": "1.9.1"
}
},
"has-flag": {
"version": "2.0.0",
"resolved": "https://registry.npmjs.org/has-flag/-/has-flag-2.0.0.tgz",
"integrity": "sha1-6CB68cx7MNRGzHC3NLXovhj4jVE=",
"dev": true
},
"supports-color": {
"version": "0.2.0",
"resolved": "https://registry.npmjs.org/supports-color/-/supports-color-0.2.0.tgz",
"integrity": "sha1-2S3iaU6z9nMjlz1649i1W0wiGQo="
"version": "4.5.0",
"resolved": "https://registry.npmjs.org/supports-color/-/supports-color-4.5.0.tgz",
"integrity": "sha1-vnoN5ITexcXN34s9WRJQRJEvY1s=",
"dev": true,
"requires": {
"has-flag": "2.0.0"
}
}
}
},
@ -442,7 +450,6 @@
"resolved": "https://registry.npmjs.org/concurrently/-/concurrently-3.5.1.tgz",
"integrity": "sha512-689HrwGw8Rbk1xtV9C4dY6TPJAvIYZbRbnKSAtfJ7tHqICFGoZ0PCWYjxfmerRyxBG0o3sbG3pe7N8vqPwIHuQ==",
"requires": {
"chalk": "0.5.1",
"commander": "2.6.0",
"date-fns": "1.29.0",
"lodash": "4.17.4",
@ -1346,14 +1353,6 @@
"function-bind": "1.1.1"
}
},
"has-ansi": {
"version": "0.1.0",
"resolved": "https://registry.npmjs.org/has-ansi/-/has-ansi-0.1.0.tgz",
"integrity": "sha1-hPJlqujA5qiKEtcCKJS3VoiUxi4=",
"requires": {
"ansi-regex": "0.2.1"
}
},
"has-flag": {
"version": "1.0.0",
"resolved": "https://registry.npmjs.org/has-flag/-/has-flag-1.0.0.tgz",
@ -2855,14 +2854,6 @@
"safe-buffer": "5.1.1"
}
},
"strip-ansi": {
"version": "0.3.0",
"resolved": "https://registry.npmjs.org/strip-ansi/-/strip-ansi-0.3.0.tgz",
"integrity": "sha1-JfSOoiynkYfzF0pNuHWTR7sSYiA=",
"requires": {
"ansi-regex": "0.2.1"
}
},
"strip-bom": {
"version": "3.0.0",
"resolved": "https://registry.npmjs.org/strip-bom/-/strip-bom-3.0.0.tgz",

9
package.json
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@ -11,10 +11,13 @@
"description": "A collection of useful Javascript snippets.",
"version": "1.0.0",
"main": "index.js",
"devDependencies": {},
"devDependencies": {
"chalk": "^2.3.0"
},
"scripts": {
"build-list": "node ./scripts/builder.js",
"lint": "node ./scripts/lintSnippet.js",
"builder": "node ./scripts/build-script.js",
"linter": "node ./scripts/lint-script.js",
"tagger": "node ./scripts/tag-script.js",
"start": "concurrently --kill-others \"nodemon -e js,md -i README.md -x \\\"npm run build-list\\\"\" \"live-server ./build\""
},
"repository": {

79
scripts/build-script.js Normal file
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@ -0,0 +1,79 @@
/*
This is the builder script that generates the README file.
Run using `npm run builder`.
*/
// Load modules
const fs = require('fs-extra'), path = require('path'), chalk = require('chalk');
// Set variables for paths
const snippetsPath = './snippets', staticPartsPath = './static-parts';
// Set variables for script
let snippets = {}, startPart = '', endPart = '', output = '', tagDbData = {};
// Load helper functions (these are from existing snippets in 30 seconds of code!)
const objectFromPairs = arr => arr.reduce((a, v) => (a[v[0]] = v[1], a), {});
const capitalize = (str, lowerRest = false) => str.slice(0, 1).toUpperCase() + (lowerRest ? str.slice(1).toLowerCase() : str.slice(1));
// Start the timer of the script
console.time('Builder');
// Synchronously read all snippets and sort them as necessary (case-insensitive)
try {
let snippetFilenames = fs.readdirSync(snippetsPath);
snippetFilenames.sort((a, b) => {
a = a.toLowerCase();
b = b.toLowerCase();
if (a < b) return -1;
if (a > b) return 1;
return 0;
});
// Store the data read from each snippet in the appropriate object
for(let snippet of snippetFilenames) snippets[snippet] = fs.readFileSync(path.join(snippetsPath,snippet),'utf8');
}
catch (err){ // Handle errors (hopefully not!)
console.log(`${chalk.red('ERROR!')} During snippet loading: ${err}`);
process.exit(1);
}
// Load static parts for the README file
try {
startPart = fs.readFileSync(path.join(staticPartsPath,'README-start.md'),'utf8');
endPart = fs.readFileSync(path.join(staticPartsPath,'README-end.md'),'utf8');
}
catch (err){ // Handle errors (hopefully not!)
console.log(`${chalk.red('ERROR!')} During static part loading: ${err}`);
process.exit(1);
}
// Load tag data from the database
try {
tagDbData = objectFromPairs(fs.readFileSync('tag_database','utf8').split('\n').slice(0,-1).map(v => v.split(':').slice(0,2)));
}
catch (err){ // Handle errors (hopefully not!)
console.log(`${chalk.red('ERROR!')} During tag database loading: ${err}`);
process.exit(1);
}
// Create the output for the README file
try {
// Add the start static part
output += `${startPart+'\n'}`;
// Loop over tags and snippets to create the table of contents
for(let tag of [...new Set(Object.entries(tagDbData).map(t => t[1]))].filter(v => v).sort((a,b) => a.localeCompare(b))){
output +=`### ${capitalize(tag, true)}\n`;
for(let taggedSnippet of Object.entries(tagDbData).filter(v => v[1] === tag))
output += `* [${taggedSnippet[0][0].toUpperCase() + taggedSnippet[0].replace(/-/g,' ').slice(1)}](#${taggedSnippet[0].replace(/\(/g,'').replace(/\)/g,'').toLowerCase()})\n`
output += '\n';
}
// Loop over tags and snippets to create the list of snippets
for(let tag of [...new Set(Object.entries(tagDbData).map(t => t[1]))].filter(v => v).sort((a,b) => a.localeCompare(b))){
output +=`## ${capitalize(tag, true)}\n`;
for(let taggedSnippet of Object.entries(tagDbData).filter(v => v[1] === tag))
output += `\n${snippets[taggedSnippet[0]+'.md']+'\n[⬆ back to top](#table-of-contents)\n'}`;
}
// Add the ending static part
output += `\n${endPart+'\n'}`;
// Write to the README file
fs.writeFileSync('README.md', output);
}
catch (err){ // Handle errors (hopefully not!)
console.log(`${chalk.red('ERROR!')} During README generation: ${err}`);
process.exit(1);
}
// Log a success message
console.log(`${chalk.green('SUCCESS!')} README file generated!`);
// Log the time taken
console.timeEnd('Builder');

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scripts/builder.js
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@ -1,57 +0,0 @@
var fs = require('fs-extra');
var path = require('path');
var snippetsPath = './snippets';
var staticPartsPath = './static-parts';
var snippets = {}, startPart = '', endPart = '', output = '';
console.time('Builder');
try {
var snippetFilenames = fs.readdirSync(snippetsPath);
snippetFilenames.sort((a, b) => {
a = a.toLowerCase();
b = b.toLowerCase();
if (a < b) {
return -1;
}
if (a > b) {
return 1;
}
return 0;
});
for(var snippet of snippetFilenames){
snippets[snippet] = fs.readFileSync(path.join(snippetsPath,snippet),'utf8');
}
}
catch (err){
console.log('Error during snippet loading: '+err);
process.exit(1);
}
try {
startPart = fs.readFileSync(path.join(staticPartsPath,'README-start.md'),'utf8');
endPart = fs.readFileSync(path.join(staticPartsPath,'README-end.md'),'utf8');
}
catch (err){
console.log('Error during static part loading: '+err);
process.exit(1);
}
try {
output += `${startPart+'\n'}`;
for(var snippet of Object.entries(snippets))
output += `* [${snippet[0][0].toUpperCase() + snippet[0].replace(/-/g,' ').slice(1,snippet[0].length-3)}](#${snippet[0].slice(0,snippet[0].length-3).replace(/\(/g,'').replace(/\)/g,'').toLowerCase()})\n`
output += '\n';
for(var snippet of Object.entries(snippets))
output += `${snippet[1]+'\n[⬆ back to top](#table-of-contents)\n'}`;
output += `${endPart+'\n'}`;
fs.writeFileSync('README.md', output);
}
catch (err){
console.log('Error during README generation: '+err);
process.exit(1);
}
console.timeEnd('Builder');

44
scripts/lint-script.js Normal file
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@ -0,0 +1,44 @@
/*
This is the linter script that lints snippets.
Run using `npm run linter`.
*/
// Load modules
const fs = require('fs-extra'), cp = require('child_process'), path = require('path');
// Set variables for paths
var snippetsPath = './snippets';
// Read files, lint each one individually and update
try {
let snippetFilenames = fs.readdirSync(snippetsPath);
snippetFilenames.sort((a, b) => {
a = a.toLowerCase();
b = b.toLowerCase();
if (a < b) return -1;
if (a > b) return 1;
return 0;
});
// Read each file, get its code, write it to a temporary file, pass it through
// semistandard, get the output from the file, update the original file.
for(let snippet of snippetFilenames){
// Start a timer for the file
console.time(`Linter (${snippet})`);
// Synchronously read data from the snippet, get the code, write it to a temporary file
let snippetData = fs.readFileSync(path.join(snippetsPath,snippet),'utf8');
let originalCode = snippetData.slice(snippetData.indexOf('```js')+5,snippetData.lastIndexOf('```'));
fs.writeFileSync(`${snippet}.temp.js`,`${originalCode}`);
// Run semistandard asynchronously (only way this manages to run), get linted code
// and write back to the original snippet file. Remove temporary file
cp.exec(`semistandard "${snippet}.temp.js" --fix`,{},(error, stdOut, stdErr) => {
let lintedCode = fs.readFileSync(`${snippet}.temp.js`,'utf8');
fs.writeFile(path.join(snippetsPath,snippet), `${snippetData.slice(0, snippetData.indexOf('```js')+5)+lintedCode+'```\n'}`);
fs.unlink(`${snippet}.temp.js`);
// Log a success message
console.log(`${chalk.red('SUCCESS!')} Linted snippet: ${snippet}`);
// Log the time taken for the file
console.timeEnd(`Linter (${snippet})`);
});
}
}
catch (err){ // Handle errors (hopefully not!)
console.log(`${chalk.red('ERROR!')} During linting: ${err}`);
process.exit(1);
}

31
scripts/lintSnippet.js
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@ -1,31 +0,0 @@
var fs = require('fs-extra');
var cp = require('child_process');
var path = require('path');
var snippetsPath = './snippets';
var snippetFilename = '';
console.time('Linter');
if(process.argv.length < 3){
console.log('Please specify the filename of a snippet to be linted.');
console.log('Example usage: npm run lint "snippet-file.md"');
process.exit(0);
}
else {
snippetFilename = process.argv[2];
let snippetData = fs.readFileSync(path.join(snippetsPath,snippetFilename),'utf8');
try {
let originalCode = snippetData.slice(snippetData.indexOf('```js')+5,snippetData.lastIndexOf('```'));
fs.writeFileSync('currentSnippet.js',`${originalCode}`);
cp.exec('semistandard "currentSnippet.js" --fix',{},(error, stdOut, stdErr) => {
let lintedCode = fs.readFileSync('currentSnippet.js','utf8');
fs.writeFile(path.join(snippetsPath,snippetFilename), `${snippetData.slice(0, snippetData.indexOf('```js')+5)+lintedCode+'```\n'}`);
console.timeEnd('Linter');
});
}
catch (err){
console.log('Error during snippet loading: '+err);
process.exit(1);
}
}

67
scripts/tag-script.js Normal file
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@ -0,0 +1,67 @@
/*
This is the tagger script that updates the tag_databse file and logs stats for snippet tags.
Run using `npm run tagger`.
*/
// Load modules
const fs = require('fs-extra'), path = require('path'), chalk = require('chalk');
// Set variables for paths
const snippetsPath = './snippets';
// Set variables for script
let snippets = {}, output = '', tagDbData = {}, missingTags = 0, tagDbStats = {};
// Load helper functions (these are from existing snippets in 30 seconds of code!)
const objectFromPairs = arr => arr.reduce((a, v) => (a[v[0]] = v[1], a), {});
const countOccurrences = (arr, value) => arr.reduce((a, v) => v === value ? a + 1 : a + 0, 0);
// Start the timer of the script
console.time('Tagger');
// Synchronously read all snippets and sort them as necessary (case-insensitive)
try {
let snippetFilenames = fs.readdirSync(snippetsPath);
snippetFilenames.sort((a, b) => {
a = a.toLowerCase();
b = b.toLowerCase();
if (a < b) return -1;
if (a > b) return 1;
return 0;
});
// Store the data read from each snippet in the appropriate object
for(let snippet of snippetFilenames) snippets[snippet] = fs.readFileSync(path.join(snippetsPath,snippet),'utf8');
}
catch (err){ // Handle errors (hopefully not!)
console.log(`${chalk.red('ERROR!')} During snippet loading: ${err}`);
process.exit(1);
}
// Load tag data from the database
try {
tagDbData = objectFromPairs(fs.readFileSync('tag_database','utf8').split('\n').slice(0,-1).map(v => v.split(':').slice(0,2)));
tagDbStats = Object.entries(tagDbData).sort((a,b) => a[1].localeCompare(b[1])).reduce((acc, val) => {acc.hasOwnProperty(val[1]) ? acc[val[1]]++ : acc[val[1]] = 1; return acc;}, {});
}
catch (err){ // Handle errors (hopefully not!)
console.log(`${chalk.red('ERROR!')} During tag database loading: ${err}`);
process.exit(1);
}
// Update the listing of snippets in tag_database and log the statistics, along with missing scripts
try {
for(let snippet of Object.entries(snippets))
if(tagDbData.hasOwnProperty(snippet[0].slice(0,-3)) && tagDbData[snippet[0].slice(0,-3)].trim())
output += `${snippet[0].slice(0,-3)}:${tagDbData[snippet[0].slice(0,-3)].trim()}\n`;
else {
output += `${snippet[0].slice(0,-3)}:\n`;
missingTags++;
console.log(`${chalk.yellow('Tag missing:')} ${snippet[0].slice(0,-3)}`);
}
// Write to tag_database
fs.writeFileSync('tag_database', output);
}
catch (err){ // Handle errors (hopefully not!)
console.log(`${chalk.red('ERROR!')} During tag_database generation: ${err}`);
process.exit(1);
}
// Log statistics for the tag_database file
console.log(`\n${chalk.bgWhite(chalk.black('=== TAG STATS ==='))}`)
for(let tagData of Object.entries(tagDbStats).filter(v => v[0] !== 'undefined'))
console.log(`${chalk.green(tagData[0])}: ${tagData[1]} snippets`);
console.log(`${chalk.blue('Untagged snippets:')} ${missingTags}\n`);
// Log a success message
console.log(`${chalk.green('SUCCESS!')} tag_database file updated!`);
// Log the time taken
console.timeEnd('Tagger');

2
snippets/array-concatenation.md
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@ -1,6 +1,6 @@
### Array concatenation
Use `Array.concat()` to concatenate and array with any additional arrays and/or values, specified in `args`.
Use `Array.concat()` to concatenate an array with any additional arrays and/or values, specified in `args`.
```js
const arrayConcat = (arr, ...args) => arr.concat(...args);

2
snippets/array-difference.md
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@ -3,6 +3,6 @@
Create a `Set` from `b`, then use `Array.filter()` on `a` to only keep values not contained in `b`.
```js
const difference = (a, b) => { const s = new Set(b); return a.filter(x => !s.has(x)); }
const difference = (a, b) => { const s = new Set(b); return a.filter(x => !s.has(x)); };
// difference([1,2,3], [1,2]) -> [3]
```

2
snippets/array-intersection.md
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@ -3,6 +3,6 @@
Create a `Set` from `b`, then use `Array.filter()` on `a` to only keep values contained in `b`.
```js
const intersection = (a, b) => { const s = new Set(b); return a.filter(x => s.has(x)); }
const intersection = (a, b) => { const s = new Set(b); return a.filter(x => s.has(x)); };
// intersection([1,2,3], [4,3,2]) -> [2,3]
```

2
snippets/array-union.md
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@ -3,6 +3,6 @@
Create a `Set` with all values of `a` and `b` and convert to an array.
```js
const union = (a, b) => Array.from(new Set([...a, ...b]))
const union = (a, b) => Array.from(new Set([...a, ...b]));
// union([1,2,3], [4,3,2]) -> [1,2,3,4]
```

9
snippets/collatz-algorithm.md Normal file
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@ -0,0 +1,9 @@
### Collatz algorithm
If `n` is even, return `n/2`. Otherwise return `3n+1`.
```js
const collatz = n => (n % 2 == 0) ? (n / 2) : (3 * n + 1);
// collatz(8) --> 4
// collatz(5) --> 16
```

11
snippets/curry.md
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@ -6,13 +6,10 @@ Otherwise return a curried function `f` that expects the rest of the arguments.
If you want to curry a function that accepts a variable number of arguments (a variadic function, e.g. `Math.min()`), you can optionally pass the number of arguments to the second parameter `arity`.
```js
const curry = (f, arity = f.length, next) =>
(next = prevArgs =>
nextArg => {
const args = [ ...prevArgs, nextArg ];
return args.length >= arity ? f(...args) : next(args);
}
)([]);
const curry = (fn, arity = fn.length, ...args) =>
arity <= args.length
? fn(...args)
: curry.bind(null, fn, arity, ...args)
// curry(Math.pow)(2)(10) -> 1024
// curry(Math.min, 3)(10)(50)(2) -> 2
```

6
snippets/drop-elements-in-array.md
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@ -4,9 +4,9 @@ Loop through the array, using `Array.shift()` to drop the first element of the a
Returns the remaining elements.
```js
const dropElements = (arr,func) => {
while(arr.length > 0 && !func(arr[0])) arr.shift();
const dropElements = (arr, func) => {
while (arr.length > 0 && !func(arr[0])) arr.shift();
return arr;
}
};
// dropElements([1, 2, 3, 4], n => n >= 3) -> [3,4]
```

2
snippets/element-is-visible-in-viewport.md
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@ -12,7 +12,7 @@ const elementIsVisibleInViewport = (el, partiallyVisible = false) => {
? ((top > 0 && top < innerHeight) || (bottom > 0 && bottom < innerHeight)) &&
((left > 0 && left < innerWidth) || (right > 0 && right < innerWidth))
: top >= 0 && left >= 0 && bottom <= innerHeight && right <= innerWidth;
}
};
// e.g. 100x100 viewport and a 10x10px element at position {top: -1, left: 0, bottom: 9, right: 10}
// elementIsVisibleInViewport(el) -> false (not fully visible)
// elementIsVisibleInViewport(el, true) -> true (partially visible)

10
snippets/fill-array.md Normal file
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@ -0,0 +1,10 @@
### Fill array
Use `Array.map()` to map values between `start` (inclusive) and `end` (exclusive) to `value`.
Omit `start` to start at the first element and/or `end` to finish at the last.
```js
const fillArray = (arr, value, start = 0, end = arr.length) =>
arr.map((v, i) => i >= start && i < end ? value : v);
// fillArray([1,2,3,4],'8',1,3) -> [1,'8','8',4]
```

13
snippets/flatten-array-up-to-depth.md Normal file
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@ -0,0 +1,13 @@
### Flatten array up to depth
Use recursion, decrementing `depth` by 1 for each level of depth.
Use `Array.reduce()` and `Array.concat()` to merge elements or arrays.
Base case, for `depth` equal to `1` stops recursion.
Omit the second element, `depth` to flatten only to a depth of `1` (single flatten).
```js
const flattenDepth = (arr, depth = 1) =>
depth != 1 ? arr.reduce((a, v) => a.concat(Array.isArray(v) ? flattenDepth(v, depth - 1) : v), [])
: arr.reduce((a, v) => a.concat(v), []);
// flattenDepth([1,[2],[[[3],4],5]], 2) -> [1,2,[3],4,5]
```

6
snippets/group-by.md
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@ -5,10 +5,8 @@ Use `Array.reduce()` to create an object, where the keys are produced from the m
```js
const groupBy = (arr, func) =>
(typeof func === 'function' ? arr.map(func) : arr.map(val => val[func]))
.reduce((acc, val, i) => {
acc[val] = acc[val] === undefined ? [arr[i]] : acc[val].concat(arr[i]); return acc;
}, {});
arr.map(typeof func === 'function' ? func : val => val[func])
.reduce((acc, val, i) => { acc[val] = (acc[val] || []).concat(arr[i]); return acc; }, {});
// groupBy([6.1, 4.2, 6.3], Math.floor) -> {4: [4.2], 6: [6.1, 6.3]}
// groupBy(['one', 'two', 'three'], 'length') -> {3: ['one', 'two'], 5: ['three']}
```

2
snippets/is-array.md
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@ -3,7 +3,7 @@
Use `Array.isArray()` to check if a value is classified as an array.
```js
const isArray = val => val && Array.isArray(val);
const isArray = val => !!val && Array.isArray(val);
// isArray(null) -> false
// isArray([1]) -> true
```

8
snippets/ordinal-suffix-of-number.md
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@ -7,9 +7,9 @@ If digit is found in teens pattern, use teens ordinal.
```js
const toOrdinalSuffix = num => {
const int = parseInt(num), digits = [(int % 10), (int % 100)],
ordinals = ["st", "nd", "rd", "th"], oPattern = [1,2,3,4],
tPattern = [11, 12, 13, 14, 15, 16, 17, 18, 19]
return oPattern.includes(digits[0]) && !tPattern.includes(digits[1]) ? int + ordinals[digits[0]-1] : int + ordinals[3];
}
ordinals = ['st', 'nd', 'rd', 'th'], oPattern = [1, 2, 3, 4],
tPattern = [11, 12, 13, 14, 15, 16, 17, 18, 19];
return oPattern.includes(digits[0]) && !tPattern.includes(digits[1]) ? int + ordinals[digits[0] - 1] : int + ordinals[3];
};
// toOrdinalSuffix("123") -> "123rd"
```

0
snippets/redirect-to-url.md → snippets/redirect-to-URL.md
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2
snippets/standard-deviation.md
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@ -11,7 +11,7 @@ const standardDeviation = (arr, usePopulation = false) => {
arr.reduce((acc, val) => acc.concat(Math.pow(val - mean, 2)), [])
.reduce((acc, val) => acc + val, 0) / (arr.length - (usePopulation ? 0 : 1))
);
}
};
// standardDeviation([10,2,38,23,38,23,21]) -> 13.284434142114991 (sample)
// standardDeviation([10,2,38,23,38,23,21], true) -> 12.29899614287479 (population)
```

1
snippets/take.md
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@ -4,7 +4,6 @@ Use `Array.slice()` to create a slice of the array with `n` elements taken from
```js
const take = (arr, n = 1) => arr.slice(0, n);
// take([1, 2, 3], 5) -> [1, 2, 3]
// take([1, 2, 3], 0) -> []
```

81
tag_database Normal file
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@ -0,0 +1,81 @@
anagrams-of-string-(with-duplicates):string
array-concatenation:array
array-difference:array
array-intersection:array
array-union:array
average-of-array-of-numbers:array
bottom-visible:browser
capitalize-first-letter-of-every-word:string
capitalize-first-letter:string
chain-asynchronous-functions:function
check-for-palindrome:string
chunk-array:array
collatz-algorithm:math
compact:array
count-occurrences-of-a-value-in-array:array
current-URL:browser
curry:function
deep-flatten-array:array
distance-between-two-points:math
divisible-by-number:math
drop-elements-in-array:array
element-is-visible-in-viewport:browser
escape-regular-expression:utility
even-or-odd-number:math
factorial:math
fibonacci-array-generator:math
fill-array:array
filter-out-non-unique-values-in-an-array:array
flatten-array-up-to-depth:array
flatten-array:array
get-max-value-from-array:array
get-min-value-from-array:array
get-native-type-of-value:utility
get-scroll-position:browser
greatest-common-divisor-(GCD):math
group-by:array
hamming-distance:math
head-of-list:array
initial-of-list:array
initialize-array-with-range:array
initialize-array-with-values:array
is-array:utility
is-boolean:utility
is-function:utility
is-number:utility
is-string:utility
is-symbol:utility
last-of-list:array
measure-time-taken-by-function:utility
median-of-array-of-numbers:array
object-from-key-value-pairs:object
object-to-key-value-pairs:object
ordinal-suffix-of-number:utility
percentile:math
pick:array
pipe:function
powerset:math
promisify:function
random-integer-in-range:utility
random-number-in-range:utility
redirect-to-URL:browser
reverse-a-string:string
RGB-to-hexadecimal:utility
run-promises-in-series:function
scroll-to-top:browser
shuffle-array:array
similarity-between-arrays:array
sleep:function
sort-characters-in-string-(alphabetical):string
standard-deviation:math
sum-of-array-of-numbers:array
swap-values-of-two-variables:utility
tail-of-list:array
take:array
truncate-a-string:string
unique-values-of-array:array
URL-parameters:utility
UUID-generator:utility
validate-email:utility
validate-number:utility
value-or-default:utility

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yarn.lock
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