update snippets 62-78
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committed by
Agamemnon Zorbas
parent
32fa5a9773
commit
d0a8c3b238
@ -9,5 +9,8 @@ const JSONToDate = arr => {
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const dt = new Date(parseInt(arr.toString().substr(6)));
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return `${dt.getDate()}/${dt.getMonth() + 1}/${dt.getFullYear()}`;
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};
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// JSONToDate(/Date(1489525200000)/) -> "14/3/2017"
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```
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```js
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JSONToDate(/Date(1489525200000)/) -> "14/3/2017"
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```
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@ -6,12 +6,15 @@ Use arithmetic comparison to check if the given number is in the specified range
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If the second parameter, `end`, is not specified, the range is considered to be from `0` to `start`.
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```js
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const inRange = (n, start, end = null) => {
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if (end && start > end) end = [start, start = end][0];
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return (end == null) ? (n >= 0 && n < start) : (n >= start && n < end);
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};
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// inRange(3, 2, 5) -> true
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// inRange(3, 4) -> true
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// inRange(2, 3, 5) -> false
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// inrange(3, 2) -> false
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const inRange = (n, start, end=null) => {
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if(end && start > end) end = [start, start=end][0];
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return (end == null) ? (n>=0 && n<start) : (n>=start && n<end);
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}
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```
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```js
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inRange(3, 2, 5) // true
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inRange(3, 4) // true
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inRange(2, 3, 5) // false
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inrange(3, 2) // false
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```
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@ -9,5 +9,5 @@ const initialize2DArray = (w, h, val = null) => Array(h).fill().map(() => Array(
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```
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```js
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initializeArrayWithRange(2, 2, 0) -> [[0,0], [0,0]]
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initialize2DArray(2, 2, 0) -> [[0,0], [0,0]]
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```
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@ -8,6 +8,9 @@ You can omit `start` to use a default value of `0`.
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```js
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const initializeArrayWithRange = (end, start = 0) =>
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Array.from({ length: (end + 1) - start }).map((v, i) => i + start);
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// initializeArrayWithRange(5) -> [0,1,2,3,4,5]
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// initializeArrayWithRange(7, 3) -> [3,4,5,6,7]
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```
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```js
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initializeArrayWithRange(5) -> [0,1,2,3,4,5]
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initializeArrayWithRange(7, 3) -> [3,4,5,6,7]
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```
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@ -7,5 +7,8 @@ You can omit `value` to use a default value of `0`.
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```js
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const initializeArrayWithValues = (n, value = 0) => Array(n).fill(value);
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// initializeArrayWithValues(5, 2) -> [2,2,2,2,2]
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```
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```js
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initializeArrayWithValues(5, 2) -> [2,2,2,2,2]
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```
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@ -6,5 +6,8 @@ Create a `Set` from `b`, then use `Array.filter()` on `a` to only keep values co
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```js
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const intersection = (a, b) => { const s = new Set(b); return a.filter(x => s.has(x)); };
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// intersection([1,2,3], [4,3,2]) -> [2,3]
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```
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```js
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intersection([1,2,3], [4,3,2]) -> [2,3]
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```
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@ -6,8 +6,11 @@ Convert the given number into an array of digits. Use `Math.pow()` to get the ap
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```js
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const isArmstrongNumber = digits =>
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(arr => arr.reduce((a, d) => a + Math.pow(parseInt(d), arr.length), 0) == digits)((digits + '').split(''));
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// isArmstrongNumber(1634) -> true
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// isArmstrongNumber(371) -> true
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// isArmstrongNumber(56) -> false
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( arr => arr.reduce( ( a, d ) => a + Math.pow( parseInt( d ), arr.length ), 0 ) == digits ? true : false )( ( digits+'' ).split( '' ) );
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```
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```js
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isArmstrongNumber(1634) // true
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isArmstrongNumber(371) // true
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isArmstrongNumber(56) // false
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```
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@ -6,6 +6,9 @@ Use `Array.isArray()` to check if a value is classified as an array.
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```js
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const isArray = val => !!val && Array.isArray(val);
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// isArray(null) -> false
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// isArray([1]) -> true
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```
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```js
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isArray(null) -> false
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isArray([1]) -> true
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```
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@ -6,6 +6,9 @@ Use `typeof` to check if a value is classified as a boolean primitive.
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```js
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const isBoolean = val => typeof val === 'boolean';
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// isBoolean(null) -> false
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// isBoolean(false) -> true
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```
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```js
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isBoolean(null) -> false
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isBoolean(false) -> true
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```
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@ -6,5 +6,8 @@ Use the modulo operator (`%`) to check if the remainder is equal to `0`.
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```js
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const isDivisible = (dividend, divisor) => dividend % divisor === 0;
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// isDivisible(6,3) -> true
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```
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```js
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isDivisible(6,3) -> true
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```
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@ -7,5 +7,8 @@ Returns `true` if the number is even, `false` if the number is odd.
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```js
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const isEven = num => num % 2 === 0;
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// isEven(3) -> false
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```
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```js
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isEven(3) -> false
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```
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@ -6,6 +6,9 @@ Use `typeof` to check if a value is classified as a function primitive.
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```js
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const isFunction = val => val && typeof val === 'function';
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// isFunction('x') -> false
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// isFunction(x => x) -> true
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```
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```js
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isFunction('x') -> false
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isFunction(x => x) -> true
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```
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@ -6,6 +6,9 @@ Use `typeof` to check if a value is classified as a number primitive.
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```js
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const isNumber = val => typeof val === 'number';
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// isNumber('1') -> false
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// isNumber(1) -> true
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```
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```js
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isNumber('1') -> false
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isNumber(1) -> true
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```
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@ -11,6 +11,9 @@ const isPrime = num => {
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for (var i = 2; i * i <= boundary; i++) if (num % i == 0) return false;
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return num >= 2;
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};
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// isPrime(11) -> true
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// isPrime(12) -> false
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```
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```js
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isPrime(11) -> true
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isPrime(12) -> false
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```
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@ -6,6 +6,9 @@ Use `typeof` to check if a value is classified as a string primitive.
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```js
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const isString = val => typeof val === 'string';
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// isString(10) -> false
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// isString('10') -> true
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```
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```js
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isString(10) -> false
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isString('10') -> true
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```
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@ -6,6 +6,9 @@ Use `typeof` to check if a value is classified as a symbol primitive.
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```js
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const isSymbol = val => typeof val === 'symbol';
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// isSymbol('x') -> false
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// isSymbol(Symbol('x')) -> true
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```
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```js
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isSymbol('x') -> false
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isSymbol(Symbol('x')) -> true
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```
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