Counts the occurences of a value in an array.
+Counts the occurrences of a value in an array.
Use Array.reduce() to increment a counter each time you encounter the specific value inside the array.
const countOccurrences = (arr, value) => arr.reduce((a, v) => v === value ? a + 1 : a + 0, 0);
// countOccurrences([1,1,2,1,2,3], 1) -> 3
@@ -271,7 +275,7 @@ Use Array.reduce() to create an object, where the keys are produced
// initial([1,2,3]) -> [1,2]
Initialized an array containing the numbers in the specified range.
+Initializes an array containing the numbers in the specified range.
Use Array(end-start) to create an array of the desired length, Array.map() to fill with the desired values in a range.
You can omit start to use a default value of 0.
const initializeArrayWithRange = (end, start = 0) =>
@@ -297,6 +301,16 @@ You can omit value to use a default value of 0.
const last = arr => arr[arr.length - 1];
// last([1,2,3]) -> 3
+Maps the values of an array to an object using a function, where the key-value pairs consist of the original value as the key and the mapped value.
+Use an anonymous inner function scope to declare an undefined memory space, using closures to store a return value. Use a new Array to stor the array with a map of the function over its data set and a comma operator to return a second step, without needing to move from one context to another (due to closures and order of operations).
const mapObject = (arr, fn) =>
+ (a => (a = [arr, arr.map(fn)], a[0].reduce( (acc,val,ind) => (acc[val] = a[1][ind], acc), {}) )) ( );
+/*
+const squareIt = arr => mapObject(arr, a => a*a)
+squareIt([1,2,3]) // { 1: 1, 2: 4, 3: 9 }
+*/
+Returns the nth element of an array.
Use Array.slice() to get an array containing the nth element at the first place.
@@ -372,7 +386,7 @@ This method also works with strings.
Returns an array with n elements removed from the beggining.
+Returns an array with n elements removed from the beginning.
Use Array.slice() to create a slice of the array with n elements taken from the beginning.
const take = (arr, n = 1) => arr.slice(0, n);
// take([1, 2, 3], 5) -> [1, 2, 3]
@@ -419,7 +433,7 @@ If lengths of the argument-arrays vary, undefined is used where no
document.documentElement.clientHeight + window.scrollY >= document.documentElement.scrollHeight || document.documentElement.clientHeight;
// bottomVisible() -> true
Returns the current URL.
Use window.location.href to get current URL.
const currentURL = () => window.location.href;
@@ -780,7 +794,7 @@ const JSONToFile = (obj, filename) => fs.writeFile(`${filename}.json`, JSON.s
Returns an array of lines from the specified file.
Use readFileSync function in fs node package to create a Buffer from a file.
convert buffer to string using toString(encoding) function.
-creating an array from contents of file by spliting file content line by line(each \n).
+creating an array from contents of file by spliting file content line by line (each \n).
const fs = require('fs');
const readFileLines = filename => fs.readFileSync(filename).toString('UTF8').split('\n');
/*
@@ -797,7 +811,7 @@ console.log(arr) // -> ['line1', 'line2', 'line3']
cleanObj
Removes any properties except the ones specified from a JSON object.
Use Object.keys() method to loop over given json object and deleting keys that are not included in given array.
-also if you give it a special key(childIndicator) it will search deeply inside it to apply function to inner objects too.
+Also if you give it a special key (childIndicator) it will search deeply inside it to apply function to inner objects too.
const cleanObj = (obj, keysToKeep = [], childIndicator) => {
Object.keys(obj).forEach(key => {
if (key === childIndicator) {
@@ -835,6 +849,12 @@ const b = shallowClone(a);
a === b -> false
*/
+
truthCheckCollection
+Checks if the predicate (second argument) is truthy on all elements of a collection (first argument).
+Use Array.every() to check if each passed object has the specified property and if it returns a truthy value.
+truthCheckCollection = (collection, pre) => (collection.every(obj => obj[pre]));
+// truthCheckCollection([{"user": "Tinky-Winky", "sex": "male"}, {"user": "Dipsy", "sex": "male"}], "sex") -> true
+
String
anagrams
Generates all anagrams of a string (contains duplicates).
@@ -852,7 +872,7 @@ Base cases are for string length equal to 2 or 1
Capitalize
Capitalizes the first letter of a string.
Use destructuring and toUpperCase() to capitalize first letter, ...rest to get array of characters after first letter and then Array.join('') to make it a string again.
-Omit the lowerRest parameter to keep the rest of the string intact, or set it to true to convert to lower case.
+Omit the lowerRest parameter to keep the rest of the string intact, or set it to true to convert to lowercase.
const capitalize = ([first,...rest], lowerRest = false) =>
first.toUpperCase() + (lowerRest ? rest.join('').toLowerCase() : rest.join(''));
// capitalize('myName') -> 'MyName'
@@ -873,7 +893,7 @@ Omit the lowerRest parameter to keep the rest of the string intact,
fromCamelCase
Converts a string from camelcase.
Use replace() to remove underscores, hyphens and spaces and convert words to camelcase.
-Omit the scond argument to use a default separator of _.
+Omit the second argument to use a default separator of _.
const fromCamelCase = (str, separator = '_') =>
str.replace(/([a-z\d])([A-Z])/g, '$1' + separator + '$2')
.replace(/([A-Z]+)([A-Z][a-z\d]+)/g, '$1' + separator + '$2').toLowerCase();
@@ -914,7 +934,20 @@ Return the string truncated to the desired length, with ... appende
// truncateString('boomerang', 7) -> 'boom...'
Utility
-extendHex
+coalesce
+Returns the first non-null/undefined argument.
+Use Array.find() to return the first non null/undefined argument.
+const coalesce = (...args) => args.find(_ => ![undefined, null].includes(_))
+// coalesce(null,undefined,"",NaN, "Waldo") -> ""
+
+
coalesceFactory
+Returns a customized coalesce function that returns the first argument that returns true from the provided argument validation function.
+Use Array.find() to return the first argument that returns true from the provided argument validation function.
+const coalesceFactory = valid => (...args) => args.find(valid);
+// const customCoalesce = coalesceFactory(_ => ![null, undefined, "", NaN].includes(_))
+// customCoalesce(undefined, null, NaN, "", "Waldo") //-> "Waldo"
+
+
extendHex
Extends a 3-digit color code to a 6-digit color code.
Use Array.map(), split() and Array.join() to join the mapped array for converting a 3-digit RGB notated hexadecimal color-code to the 6-digit form.
Array.slice() is used to remove # from string start since it's added once.
@@ -925,7 +958,7 @@ Return the string truncated to the desired length, with ... appende
getType
Returns the native type of a value.
-Returns lower-cased constructor name of value, "undefined" or "null" if value is undefined or null
+Returns lowercased constructor name of value, "undefined" or "null" if value is undefined or null
const getType = v =>
v === undefined ? 'undefined' : v === null ? 'null' : v.constructor.name.toLowerCase();
// getType(new Set([1,2,3])) -> "set"
@@ -934,12 +967,11 @@ 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 ?
- `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}, ${parseInt(hex.slice(1), 16) & 0x0000ff})`;
-}
+ const extendedHex = hex.slice(hex.startsWith('#') ? 1 : 0).length === 3 ? extendHex(hex) : hex;
+ return `rgb(${parseInt(extendedHex.slice(1), 16) >> 16}, ${(parseInt(extendedHex.slice(1), 16) & 0x00ff00) >> 8}, ${parseInt(extendedHex.slice(1), 16) & 0x0000ff})`;
+}
// hexToRgb('#27ae60') -> 'rgb(39, 174, 96)'
// hexToRgb('#acd') -> 'rgb(170, 204, 221)'
diff --git a/snippets/capitalize.md b/snippets/capitalize.md
index f29c933d2..d085a3034 100644
--- a/snippets/capitalize.md
+++ b/snippets/capitalize.md
@@ -3,7 +3,7 @@
Capitalizes the first letter of a string.
Use destructuring and `toUpperCase()` to capitalize first letter, `...rest` to get array of characters after first letter and then `Array.join('')` to make it a string again.
-Omit the `lowerRest` parameter to keep the rest of the string intact, or set it to `true` to convert to lower case.
+Omit the `lowerRest` parameter to keep the rest of the string intact, or set it to `true` to convert to lowercase.
```js
const capitalize = ([first,...rest], lowerRest = false) =>
diff --git a/snippets/cleanObj.md b/snippets/cleanObj.md
index 8ba4058ed..75a8e900b 100644
--- a/snippets/cleanObj.md
+++ b/snippets/cleanObj.md
@@ -3,7 +3,7 @@
Removes any properties except the ones specified from a JSON object.
Use `Object.keys()` method to loop over given json object and deleting keys that are not `include`d in given array.
-also if you give it a special key(`childIndicator`) it will search deeply inside it to apply function to inner objects too.
+Also if you give it a special key (`childIndicator`) it will search deeply inside it to apply function to inner objects too.
```js
const cleanObj = (obj, keysToKeep = [], childIndicator) => {
diff --git a/snippets/coalesce.md b/snippets/coalesce.md
new file mode 100644
index 000000000..22271dc68
--- /dev/null
+++ b/snippets/coalesce.md
@@ -0,0 +1,10 @@
+### coalesce
+
+Returns the first non-null/undefined argument.
+
+Use `Array.find()` to return the first non `null`/`undefined` argument.
+
+```js
+const coalesce = (...args) => args.find(_ => ![undefined, null].includes(_))
+// coalesce(null,undefined,"",NaN, "Waldo") -> ""
+```
diff --git a/snippets/coalesceFactory.md b/snippets/coalesceFactory.md
new file mode 100644
index 000000000..4b9a78924
--- /dev/null
+++ b/snippets/coalesceFactory.md
@@ -0,0 +1,11 @@
+### coalesceFactory
+
+Returns a customized coalesce function that returns the first argument that returns `true` from the provided argument validation function.
+
+Use `Array.find()` to return the first argument that returns `true` from the provided argument validation function.
+
+```js
+const coalesceFactory = valid => (...args) => args.find(valid);
+// const customCoalesce = coalesceFactory(_ => ![null, undefined, "", NaN].includes(_))
+// customCoalesce(undefined, null, NaN, "", "Waldo") //-> "Waldo"
+```
diff --git a/snippets/countOccurrences.md b/snippets/countOccurrences.md
index be28947f0..f55de0a62 100644
--- a/snippets/countOccurrences.md
+++ b/snippets/countOccurrences.md
@@ -1,6 +1,6 @@
### countOccurrences
-Counts the occurences of a value in an array.
+Counts the occurrences of a value in an array.
Use `Array.reduce()` to increment a counter each time you encounter the specific value inside the array.
diff --git a/snippets/current-URL.md b/snippets/currentURL.md
similarity index 100%
rename from snippets/current-URL.md
rename to snippets/currentURL.md
diff --git a/snippets/fromCamelCase.md b/snippets/fromCamelCase.md
index e9c61f1ba..e004e67ef 100644
--- a/snippets/fromCamelCase.md
+++ b/snippets/fromCamelCase.md
@@ -3,7 +3,7 @@
Converts a string from camelcase.
Use `replace()` to remove underscores, hyphens and spaces and convert words to camelcase.
-Omit the scond argument to use a default separator of `_`.
+Omit the second argument to use a default separator of `_`.
```js
const fromCamelCase = (str, separator = '_') =>
diff --git a/snippets/getType.md b/snippets/getType.md
index 3110871fb..53f660420 100644
--- a/snippets/getType.md
+++ b/snippets/getType.md
@@ -2,7 +2,7 @@
Returns the native type of a value.
-Returns lower-cased constructor name of value, "undefined" or "null" if value is undefined or null
+Returns lowercased constructor name of value, "undefined" or "null" if value is undefined or null
```js
const getType = v =>
diff --git a/snippets/hexToRGB.md b/snippets/hexToRGB.md
index e3118ecf3..273aafd21 100644
--- a/snippets/hexToRGB.md
+++ b/snippets/hexToRGB.md
@@ -6,12 +6,11 @@ Use bitwise right-shift operator and mask bits with `&` (and) operator to conver
```js
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 ?
- `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}, ${parseInt(hex.slice(1), 16) & 0x0000ff})`;
-}
+ const extendedHex = hex.slice(hex.startsWith('#') ? 1 : 0).length === 3 ? extendHex(hex) : hex;
+ return `rgb(${parseInt(extendedHex.slice(1), 16) >> 16}, ${(parseInt(extendedHex.slice(1), 16) & 0x00ff00) >> 8}, ${parseInt(extendedHex.slice(1), 16) & 0x0000ff})`;
+}
// hexToRgb('#27ae60') -> 'rgb(39, 174, 96)'
// hexToRgb('#acd') -> 'rgb(170, 204, 221)'
```
diff --git a/snippets/initializeArrayWithRange.md b/snippets/initializeArrayWithRange.md
index d90de1136..75dbc8adf 100644
--- a/snippets/initializeArrayWithRange.md
+++ b/snippets/initializeArrayWithRange.md
@@ -1,6 +1,6 @@
### initializeArrayWithRange
-Initialized an array containing the numbers in the specified range.
+Initializes an array containing the numbers in the specified range.
Use `Array(end-start)` to create an array of the desired length, `Array.map()` to fill with the desired values in a range.
You can omit `start` to use a default value of `0`.
diff --git a/snippets/mapObject.md b/snippets/mapObject.md
new file mode 100644
index 000000000..102795a73
--- /dev/null
+++ b/snippets/mapObject.md
@@ -0,0 +1,14 @@
+### mapObject
+
+Maps the values of an array to an object using a function, where the key-value pairs consist of the original value as the key and the mapped value.
+
+Use an anonymous inner function scope to declare an undefined memory space, using closures to store a return value. Use a new `Array` to stor the array with a map of the function over its data set and a comma operator to return a second step, without needing to move from one context to another (due to closures and order of operations).
+
+```js
+const mapObject = (arr, fn) =>
+ (a => (a = [arr, arr.map(fn)], a[0].reduce( (acc,val,ind) => (acc[val] = a[1][ind], acc), {}) )) ( );
+/*
+const squareIt = arr => mapObject(arr, a => a*a)
+squareIt([1,2,3]) // { 1: 1, 2: 4, 3: 9 }
+*/
+```
diff --git a/snippets/readFileLines.md b/snippets/readFileLines.md
index 288c2ebf8..6433c6059 100644
--- a/snippets/readFileLines.md
+++ b/snippets/readFileLines.md
@@ -4,7 +4,7 @@ Returns an array of lines from the specified file.
Use `readFileSync` function in `fs` node package to create a `Buffer` from a file.
convert buffer to string using `toString(encoding)` function.
-creating an array from contents of file by `split`ing file content line by line(each `\n`).
+creating an array from contents of file by `split`ing file content line by line (each `\n`).
```js
const fs = require('fs');
diff --git a/snippets/take.md b/snippets/take.md
index 85802f6a8..f6afa5dab 100644
--- a/snippets/take.md
+++ b/snippets/take.md
@@ -1,6 +1,6 @@
### take
-Returns an array with n elements removed from the beggining.
+Returns an array with n elements removed from the beginning.
Use `Array.slice()` to create a slice of the array with `n` elements taken from the beginning.
diff --git a/snippets/truthCheckCollection.md b/snippets/truthCheckCollection.md
new file mode 100644
index 000000000..82a6d26cd
--- /dev/null
+++ b/snippets/truthCheckCollection.md
@@ -0,0 +1,10 @@
+### truthCheckCollection
+
+Checks if the predicate (second argument) is truthy on all elements of a collection (first argument).
+
+Use `Array.every()` to check if each passed object has the specified property and if it returns a truthy value.
+
+ ```js
+truthCheckCollection = (collection, pre) => (collection.every(obj => obj[pre]));
+// truthCheckCollection([{"user": "Tinky-Winky", "sex": "male"}, {"user": "Dipsy", "sex": "male"}], "sex") -> true
+```
diff --git a/tag_database b/tag_database
index 3d17b3376..f48f069b3 100644
--- a/tag_database
+++ b/tag_database
@@ -9,11 +9,13 @@ capitalizeEveryWord:string
chainAsync:function
chunk:array
cleanObj:object
+coalesce:utility
+coalesceFactory:utility
collatz:math
compact:array
compose:function
countOccurrences:array
-current-URL:browser
+currentURL:browser
curry:function
deepFlatten:array
difference:array
@@ -57,6 +59,7 @@ JSONToDate:date
JSONToFile:node
last:array
lcm:math
+mapObject:array
median:math
nthElement:array
objectFromPairs:object
@@ -95,6 +98,7 @@ toCamelCase:string
toEnglishDate:date
toOrdinalSuffix:utility
truncateString:string
+truthCheckCollection:object
union:array
UUIDGenerator:utility
validateEmail:utility