Array
+Array
arrayMax
Returns the maximum value in an array.
Use Math.max() combined with the spread operator (...) to get the maximum value in the array.
const difference = (a, b) => { const s = new Set(b); return a.filter(x => !s.has(x)); };
// difference([1,2,3], [1,2,4]) -> [3]
differenceWith
Filters out all values from an array for which the comparator function does not return true.
Use Array.filter() and Array.find() to find the appropriate values.
const differenceWith = (arr, val, comp) => arr.filter(a => !val.find(b => comp(a, b)))
+// differenceWith([1, 1.2, 1.5, 3], [1.9, 3], (a,b) => Math.round(a) == Math.round(b)) -> [1, 1.2]
+distinctValuesOfArray
Returns all the distinct values of an array.
Use ES6 Set and the ...rest operator to discard all duplicated values.
dropElements
Removes elements in an array until the passed function returns true. Returns the remaining elements in the array.
Loop through the array, using Array.shift() to drop the first element of the array until the returned value from the function is true.
+
Loop through the array, using Array.slice() to drop the first element of the array until the returned value from the function is true.
Returns the remaining elements.
const dropElements = (arr, func) => {
- while (arr.length > 0 && !func(arr[0])) arr.shift();
+ while (arr.length > 0 && !func(arr[0])) arr = arr.slice(1);
return arr;
};
// dropElements([1, 2, 3, 4], n => n >= 3) -> [3,4]
dropRight
Returns a new array with n elements removed from the right
Check if n is shorter than the given array and use Array.slice() to slice it accordingly or return an empty array.
const dropRight = (arr, n = 1) => n < arr.length ? arr.slice(0, arr.length - n) : []
+//dropRight([1,2,3]) -> [1,2]
+//dropRight([1,2,3], 2) -> [1]
+//dropRight([1,2,3], 42) -> []
+everyNth
Returns every nth element in an array.
Use Array.filter() to create a new array that contains every nth element of a given array.
Array.reduce() to create an object, where the keys are produced
// initial([1,2,3]) -> [1,2]
initializeArrayWithRange
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.
+
Initializes an array containing the numbers in the specified range where start and end are inclusive.
Use Array((end + 1) - 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) =>
- Array.from({ length: end - start }).map((v, i) => i + start);
-// initializeArrayWithRange(5) -> [0,1,2,3,4]
+const initializeArrayWithRange = (end, start = 0) =>
+ Array.from({ length: (end + 1) - start }).map((v, i) => i + start);
+// initializeArrayWithRange(5) -> [0,1,2,3,4,5]
+// initializeArrayWithRange(7, 3) -> [3,4,5,6,7]
initializeArrayWithValues
Initializes and fills an array with the specified values.
@@ -332,13 +355,59 @@ Omit the second argument,n, to get the first element of the array.
Mutates the original array to filter out the values specified.
Use Array.filter() and Array.includes() to pull out the values that are not needed.
Use Array.length = 0 to mutate the passed in array by resetting it's length to zero and Array.push() to re-populate it with only the pulled values.
(For a snippet that does not mutate the original array see without)
const pull = (arr, ...args) => {
- let pulled = arr.filter((v, i) => !args.includes(v));
+ let pulled = arr.filter((v, i) => !args.toString().split(',').includes(v));
arr.length = 0; pulled.forEach(v => arr.push(v));
};
-// let myArray = ['a', 'b', 'c', 'a', 'b', 'c'];
-// pull(myArray, 'a', 'c');
-// console.log(myArray) -> [ 'b', 'b' ]
+
+// let myArray1 = ['a', 'b', 'c', 'a', 'b', 'c'];
+// pull(myArray1, 'a', 'c');
+// console.log(myArray1) -> [ 'b', 'b' ]
+
+// let myArray2 = ['a', 'b', 'c', 'a', 'b', 'c'];
+// pull(myArray2, ['a', 'c']);
+// console.log(myArray2) -> [ 'b', 'b' ]
+pullAtIndex
Mutates the original array to filter out the values at the specified indexes.
+Use Array.filter() and Array.includes() to pull out the values that are not needed.
+Use Array.length = 0 to mutate the passed in array by resetting it's length to zero and Array.push() to re-populate it with only the pulled values.
+Use Array.push() to keep track of pulled values
const pullAtIndex = (arr, pullArr) => {
+ let removed = [];
+ let pulled = arr.map((v, i) => pullArr.includes(i) ? removed.push(v) : v)
+ .filter((v, i) => !pullArr.includes(i))
+ arr.length = 0;
+ pulled.forEach(v => arr.push(v));
+ return removed;
+}
+
+// let myArray = ['a', 'b', 'c', 'd'];
+// let pulled = pullAtIndex(myArray, [1, 3]);
+
+// console.log(myArray); -> [ 'a', 'c' ]
+// console.log(pulled); -> [ 'b', 'd' ]
+pullAtValue
Mutates the original array to filter out the values specified. Returns the removed elements.
+Use Array.filter() and Array.includes() to pull out the values that are not needed.
+Use Array.length = 0 to mutate the passed in array by resetting it's length to zero and Array.push() to re-populate it with only the pulled values.
+Use Array.push() to keep track of pulled values
const pullAtValue = (arr, pullArr) => {
+ let removed = [],
+ pushToRemove = arr.forEach((v, i) => pullArr.includes(v) ? removed.push(v) : v),
+ mutateTo = arr.filter((v, i) => !pullArr.includes(v));
+ arr.length = 0;
+ mutateTo.forEach(v => arr.push(v));
+ return removed;
+}
+/*
+let myArray = ['a', 'b', 'c', 'd'];
+let pulled = pullAtValue(myArray, ['b', 'd']);
+console.log(myArray); -> [ 'a', 'c' ]
+console.log(pulled); -> [ 'b', 'd' ]
+*/
remove
Removes elements from an array for which the given function returns false.
without
Filters out the elements of an array, that have one of the specified values.
Use Array.filter() to create an array excluding(using !Array.includes()) all given values.
(For a snippet that mutates the original array see pull)
const without = (arr, ...args) => arr.filter(v => !args.includes(v));
// without([2, 1, 2, 3], 1, 2) -> [3]
undefined is used where no
Returns true if the bottom of the page is visible, false otherwise.
Use scrollY, scrollHeight and clientHeight to determine if the bottom of the page is visible.
const bottomVisible = () =>
- document.documentElement.clientHeight + window.scrollY >= document.documentElement.scrollHeight || document.documentElement.clientHeight;
+ document.documentElement.clientHeight + window.scrollY >= (document.documentElement.scrollHeight || document.documentElement.clientHeight);
// bottomVisible() -> true
currentURL
Find the middle of the array, use Array.sort() to sort the values.
Return the number at the midpoint if length is odd, otherwise the average of the two middle numbers.
const median = arr => {
- const mid = Math.floor(arr.length / 2), nums = arr.sort((a, b) => a - b);
+ const mid = Math.floor(arr.length / 2), nums = [...arr].sort((a, b) => a - b);
return arr.length % 2 !== 0 ? nums[mid] : (nums[mid - 1] + nums[mid]) / 2;
};
// median([5,6,50,1,-5]) -> 5
@@ -840,6 +910,15 @@ Also if you give it a special key (childIndicator) it will search d
const objectToPairs = obj => Object.keys(obj).map(k => [k, obj[k]]);
// objectToPairs({a: 1, b: 2}) -> [['a',1],['b',2]])
+select
Retrieve a property that indicated by the selector from object.
+If property not exists returns undefined.
const select = (from, selector) =>
+ selector.split('.').reduce((prev, cur) => prev && prev[cur], from);
+
+// const obj = {selector: {to: {val: 'val to select'}}};
+// select(obj, 'selector.to.val'); -> 'val to select'
+shallowClone
Creates a shallow clone of an object.
Use Object.assign() and an empty object ({}) to create a shallow clone of the original.
lowerRest parameter to keep the rest of the string intact,
countVowels
Retuns number of vowels in provided string.
Use a regular expression to count number of vowels (A, E, I, O, U) in a string.
const countVowels = str =>
- return (str.match(/[aeiou]/ig) || []).length;
+const countVowels = str => (str.match(/[aeiou]/ig) || []).length;
// countVowels('foobar') -> 3
// countVowels('gym') -> 0
@@ -912,9 +990,9 @@ Omit the second argument to use a default separator of _.
reverseString
Reverses a string.
-Use array destructuring and Array.reverse() to reverse the order of the characters in the string.
+
Use split('') and Array.reverse() to reverse the order of the characters in the string.
Combine characters to get a string using join('').
const reverseString = str => [...str].reverse().join('');
+const reverseString = str => str.split('').reverse().join('');
// reverseString('foobar') -> 'raboof'
sortCharactersInString
... appende
// getType(new Set([1,2,3])) -> "set"
hexToRGB
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 =>
- '#' + shortHex.slice(shortHex.startsWith('#') ? 1 : 0).split('').map(x => x+x).join('');
- 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)'
+Converts a color code to a rgb() or rgba() string if alpha value is provided.
+Use bitwise right-shift operator and mask bits with & (and) operator to convert a hexadecimal color code (with or without prefixed with #) to a string with the RGB values. If it's 3-digit color code, first convert to 6-digit version. If any alpha value is provided alongside 6-digit hex, give rgba() string in return.
+const hexToRGB = hex => {
+ let alpha = false, h = hex.slice(hex.startsWith('#') ? 1 : 0);
+ if (h.length === 3) h = [...h].map(x => x + x).join('');
+ else if (h.length === 8) alpha = true;
+ h = parseInt(h, 16);
+ return 'rgb' + (alpha ? 'a' : '') + '('
+ + (h >>> (alpha ? 24 : 16)) + ', '
+ + ((h & (alpha ? 0x00ff0000 : 0x00ff00)) >>> (alpha ? 16 : 8)) + ', '
+ + ((h & (alpha ? 0x0000ff00 : 0x0000ff)) >>> (alpha ? 8 : 0))
+ + (alpha ? `, ${(h & 0x000000ff)}` : '') + ')';
+};
+// hexToRGB('#27ae60ff') -> 'rgba(39, 174, 96, 255)'
+// hexToRGB('27ae60') -> 'rgb(39, 174, 96)'
+// hexToRGB('#fff') -> 'rgb(255, 255, 255)'
+
isArray
Checks if the given argument is an array.
@@ -1081,9 +1166,12 @@ UseNumber() to check if the coercion holds.
// validateNumber('10') -> true
- +