30 seconds of code 30 seconds of codeRemoves elements in an array until the passed function returns true. Returns the remaining elements in the array.
Returns every nth element in an array.
Use Array.filter() to create a new array that contains every nth element of a given array.
const everyNth = (arr, nth) => arr.filter((e, i) => i % nth === 0);
-// everynth([1,2,3,4,5,6], 2) -> [ 1, 3, 5 ]
+// everyNth([1,2,3,4,5,6], 2) -> [ 1, 3, 5 ]
Filters out the non-unique values in an array.
@@ -276,14 +276,14 @@ UseArray.reduce() to create an object, where the keys are produced
You can omit start to use a default value of 0.
const initializeArrayWithRange = (end, start = 0) =>
Array.from({ length: end - start }).map((v, i) => i + start);
-// initializeArrayRange(5) -> [0,1,2,3,4]
+// initializeArrayWithRange(5) -> [0,1,2,3,4]
Initializes and fills an array with the specified values.
Use Array(n) to create an array of the desired length, fill(v) to fill it with the desired values.
You can omit value to use a default value of 0.
const initializeArrayWithValues = (n, value = 0) => Array(n).fill(value);
-// initializeArray(5, 2) -> [2,2,2,2,2]
+// initializeArrayWithValues(5, 2) -> [2,2,2,2,2]
Returns a list of elements that exist in both arrays.
@@ -449,7 +449,7 @@ You can omitel to use a default value of window.
const getScrollPosition = (el = window) =>
({x: (el.pageXOffset !== undefined) ? el.pageXOffset : el.scrollLeft,
y: (el.pageYOffset !== undefined) ? el.pageYOffset : el.scrollTop});
-// getScrollPos() -> {x: 0, y: 200}
+// getScrollPosition() -> {x: 0, y: 200}
Returns an object containing the parameters of the current URL.
@@ -459,7 +459,7 @@ Passlocation.search as the argument to apply to the current
url.match(/([^?=&]+)(=([^&]*))/g).reduce(
(a, v) => (a[v.slice(0, v.indexOf('='))] = v.slice(v.indexOf('=') + 1), a), {}
);
-// getUrlParameters('http://url.com/page?name=Adam&surname=Smith') -> {name: 'Adam', surname: 'Smith'}
+// getURLParameters('http://url.com/page?name=Adam&surname=Smith') -> {name: 'Adam', surname: 'Smith'}
Redirects to a specified URL.
@@ -496,7 +496,7 @@ Scroll by a fraction of the distance from top. Usewindow.requestAnimation
const dt = new Date(parseInt(arr.toString().substr(6)));
return `${ dt.getDate() }/${ dt.getMonth() + 1 }/${ dt.getFullYear() }`
};
-// jsonToDate(/Date(1489525200000)/) -> "14/3/2017"
+// JSONToDate(/Date(1489525200000)/) -> "14/3/2017"
Converts a date from American format to English format.
@@ -558,7 +558,7 @@ The first (leftmost) function can accept one or more arguments; the remaining fu /* const add5 = x => x + 5 const multiply = (x, y) => x * y -const multiplyAndAdd5 = pipe(multiply, add5) +const multiplyAndAdd5 = pipeFunctions(multiply, add5) multiplyAndAdd5(5, 2) -> 15 */ @@ -581,7 +581,7 @@ Use the...rest operator to pass in all the parameters.
Use Array.reduce() to create a promise chain, where each promise returns the next promise when resolved.
const runPromisesInSeries = ps => ps.reduce((p, next) => p.then(next), Promise.resolve());
// const delay = (d) => new Promise(r => setTimeout(r, d))
-// series([() => delay(1000), () => delay(2000)]) -> executes each promise sequentially, taking a total of 3 seconds to complete
+// runPromisesInSeries([() => delay(1000), () => delay(2000)]) -> executes each promise sequentially, taking a total of 3 seconds to complete
Delays the execution of an asynchronous function.
@@ -600,13 +600,13 @@ async function sleepyWork() {Returns the average of an array of numbers.
Use Array.reduce() to add each value to an accumulator, initialized with a value of 0, divide by the length of the array.
const arrayAverage = arr => arr.reduce((acc, val) => acc + val, 0) / arr.length;
-// average([1,2,3]) -> 2
+// arrayAverage([1,2,3]) -> 2
Returns the sum of an array of numbers.
Use Array.reduce() to add each value to an accumulator, initialized with a value of 0.
const arraySum = arr => arr.reduce((acc, val) => acc + val, 0);
-// sum([1,2,3,4]) -> 10
+// arraySum([1,2,3,4]) -> 10
Applies the Collatz algorithm.
@@ -731,7 +731,7 @@ Then,split('') into individual characters, reverse(),
Returns a random number in the specified range.
Use Math.random() to generate a random value, map it to the desired range using multiplication.
const randomNumberInRange = (min, max) => Math.random() * (max - min) + min;
-// randomInRange(2,10) -> 6.0211363285087005
+// randomNumberInRange(2,10) -> 6.0211363285087005
Rounds a number to a specified amount of digits.
@@ -766,7 +766,7 @@ Usewindow.speechSynthesis.speak() to play the message.
msg.voice = window.speechSynthesis.getVoices()[0];
window.speechSynthesis.speak(msg);
};
-// speak('Hello, World') -> plays the message
+// speechSynthesis('Hello, World') -> plays the message
window.speechSynthesis.speak() to play the message.
Use fs.writeFile(), template literals and JSON.stringify() to write a json object to a .json file.
const fs = require('fs');
const JSONToFile = (obj, filename) => fs.writeFile(`${filename}.json`, JSON.stringify(obj, null, 2))
-// jsonToFile({test: "is passed"}, 'testJsonFile') -> writes the object to 'testJsonFile.json'
+// JSONToFile({test: "is passed"}, 'testJsonFile') -> writes the object to 'testJsonFile.json'
Returns an array of lines from the specified file.
@@ -789,7 +789,7 @@ contents of test.txt : line2 line3 ___________________________ -let arr = readFileToArray('test.txt') +let arr = readFileLines('test.txt') console.log(arr) // -> ['line1', 'line2', 'line3'] */ @@ -808,7 +808,7 @@ also if you give it a special key(childIndicator) it will search de
})
}
/*
- testObj = {a: 1, b: 2, children: {a: 1, b: 2}}
+ const testObj = {a: 1, b: 2, children: {a: 1, b: 2}}
cleanObj(testObj, ["a"],"children")
console.log(testObj)// { a: 1, children : { a: 1}}
*/
@@ -911,7 +911,7 @@ Combine characters to get a string using join('').
Return the string truncated to the desired length, with ... appended to the end or the original string.
const truncateString = (str, num) =>
str.length > num ? str.slice(0, num > 3 ? num - 3 : num) + '...' : str;
-// truncate('boomerang', 7) -> 'boom...'
+// truncateString('boomerang', 7) -> 'boom...'
... appende
Array.slice() is used to remove # from string start since it's added once.
const extendHex = shortHex =>
'#' + shortHex.slice(shortHex.startsWith('#') ? 1 : 0).split('').map(x => x+x).join('')
-// convertHex('#03f') -> '#0033ff'
-// convertHex('05a') -> '#0055aa'
+// extendHex('#03f') -> '#0033ff'
+// extendHex('05a') -> '#0055aa'
Returns the native type of a value.
@@ -934,12 +934,12 @@ Return the string truncated to the desired length, with... appende
Converts a colorcode to a rgb() string.
Use bitwise right-shift operator and mask bits with & (and) operator to convert a hexadecimal color code (prefixed with #) to a string with the RGB values. In case it's a 3-digit-colorcode, do the same with the 6-digit-colorcode extended by the extendHex() function (ref. extendHex snippet)
const hexToRgb = hex => {
- const extendHex = shortHex =>
+ const extendHex = shortHex =>
'#' + shortHex.slice(shortHex.startsWith('#') ? 1 : 0).split('').map(x => x+x).join('');
- return hex.slice(1).length==3 ?
+ return hex.slice(1).length==3 ?
`rgb(${parseInt(extendHex(hex).slice(1), 16) >> 16}, ${(parseInt(extendHex(hex).slice(1), 16) & 0x00ff00) >> 8}, ${parseInt(extendHex(hex).slice(1), 16) & 0x0000ff})`:
`rgb(${parseInt(hex.slice(1), 16) >> 16}, ${(parseInt(hex.slice(1), 16) & 0x00ff00) >> 8}, ${parseInt(hex.slice(1), 16) & 0x0000ff})`;
-}
+}
// hexToRgb('#27ae60') -> 'rgb(39, 174, 96)'
// hexToRgb('#acd') -> 'rgb(170, 204, 221)'
... appende
Converts the values of RGB components to a colorcode.
Convert given RGB parameters to hexadecimal string using bitwise left-shift operator (<<) and toString(16), then padStart(6,'0') to get a 6-digit hexadecimal value.
const RGBToHex = (r, g, b) => ((r << 16) + (g << 8) + b).toString(16).padStart(6, '0');
-// rgbToHex(255, 165, 1) -> 'ffa501'
+// RGBToHex(255, 165, 1) -> 'ffa501'
Measures the time taken by a function to execute.
@@ -1021,7 +1021,7 @@ If digit is found in teens pattern, use teens ordinal. ([1e7] + -1e3 + -4e3 + -8e3 + -1e11).replace(/[018]/g, c => (c ^ crypto.getRandomValues(new Uint8Array(1))[0] & 15 >> c / 4).toString(16) ); -// uuid() -> '7982fcfe-5721-4632-bede-6000885be57d' +// UUIDGenerator() -> '7982fcfe-5721-4632-bede-6000885be57d'Returns true if the given string is a valid email, false otherwise.
Number() to check if the coercion holds.