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value |
|---|---|---|
Mmdn_built_in_objects/jsmapsasp_67_0.txt | [ Learn W3.JS ](/w3js/default.asp "W3.JS Tutorial") [ Tutorial
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Mmdn_built_in_objects/Mmdn_built_in_objects_51_10.txt |
const arr = [42];
This creates an array with no elements and ` arr.length ` set to 42.
js
const arr = Array(42);
This is equivalent to:
js
const arr = [];
arr.length = 42;
Calling ` Array(N) ` results in a ` RangeError ` , if ` N ` is a non-whole
number whose... | |
Mmdn_built_in_objects/jsmapsasp_177_0.txt | [ Excel ](/excel/excel_exercises.php "Excel Exercises") [ Exercise
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Mmdn_built_in_objects/Mmdn_built_in_objects_101_1.txt | tries() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/entries)
6. [ ` Array.prototype.every() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/every)
7. [ ` Array.prototype.fill() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/fill)
8. [ ` Array.prototype.filter()... | |
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Mmdn_built_in_objects/Mmdn_built_in_objects_51_9.txt | res ](/en-US/docs/Web/JavaScript/Reference/Deprecated_and_obsolete_features)
## In this article
* Creating an array
* Referring to array elements
* Populating an array
* Array transformations
* Sparse arrays
* Multi-dimensional arrays
* Using arrays to store other properties
* Working with arr... | |
Mmdn_built_in_objects/Mmdn_built_in_objects_51_4.txt | erence/Operators/Logical_OR_assignment)
46. [ Multiplication (*) ](/en-US/docs/Web/JavaScript/Reference/Operators/Multiplication)
47. [ Multiplication assignment (*=) ](/en-US/docs/Web/JavaScript/Reference/Operators/Multiplication_assignment)
48. [ new ](/en-US/docs/Web/JavaScript/Reference/Operators/new)
... | |
Mmdn_built_in_objects/Mmdn_built_in_objects_27_1.txt | aScript/Reference/Global_Objects/Object/__lookupSetter__) Deprecated
5. [ ` Object.assign() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign)
6. [ ` Object.create() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/create)
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Mmdn_built_in_objects/Mmdn_built_in_objects_60_4.txt | /API/BarProp)
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Mmdn_built_in_objects/Mmdn_built_in_objects_97_1.txt | 1. _[ ` Function.prototype[@@hasInstance]() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/@@hasInstance) _
2. [ ` Function.prototype.apply() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/apply)
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Mmdn_built_in_objects/Mmdn_built_in_objects_52_2.txt | x
js
isPrototypeOf(object)
### Parameters
` object `
The object whose prototype chain will be searched.
### Return value
A boolean indicating whether the calling object ( ` this ` ) lies in the
prototype chain of ` object ` . Directly returns ` false ` when ` object ` is
not an object ... | |
Mmdn_built_in_objects/Mmdn_built_in_objects_87_11.txt | one of the elements in your array evaluate to ` false ` in a
boolean contextâif your array consists only of [ DOM ](/en-
US/docs/Web/API/Document_Object_Model) nodes, for exampleâyou can use a more
efficient idiom:
js
const divs = document.getElementsByTagName("div");
for (let i = 0, div; (div =... | |
Mmdn_built_in_objects/jsmapsasp_370_0.txt | // Create a Map
const fruits = new Map([
["apples", 500],
["bananas", 300],
["oranges", 200]
]); | |
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Mmdn_built_in_objects/322323_18_0.txt | 1 Like | |
Mmdn_built_in_objects/4usesofjavascriptsar_157_0.txt | const usersByLikes = myUsers.map(item => {
const container = {}; | |
Mmdn_built_in_objects/Mmdn_built_in_objects_51_11.txt | one of the elements in your array evaluate to ` false ` in a
boolean contextâif your array consists only of [ DOM ](/en-
US/docs/Web/API/Document_Object_Model) nodes, for exampleâyou can use a more
efficient idiom:
js
const divs = document.getElementsByTagName("div");
for (let i = 0, div; (div =... | |
Mmdn_built_in_objects/Mmdn_built_in_objects_74_1.txt | prototype[@@hasInstance]() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/@@hasInstance)
2. [ ` Function.prototype.apply() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/apply)
3. [ ` Function.prototype.bind() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/b... | |
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Mmdn_built_in_objects/Mmdn_built_in_objects_88_3.txt | aScript/Reference/Global_Objects/Array) instances takes an
integer value and returns the item at that index, allowing for positive and
negative integers. Negative integers count back from the last item in the
array.
## Try it
## Syntax
js
at(index)
### Parameters
` index `
Zero-based ... | |
Mmdn_built_in_objects/322323_13_0.txt |
This function doesn’t return anything and is also missing the braces ( ` {} `
) around the object. | |
Mmdn_built_in_objects/Mmdn_built_in_objects_73_2.txt | aScript/Reference/Global_Objects/Array/values)
43. [ ` Array.prototype.with() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/with)
6. **Inheritance**
7. **[ ` Function ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function) **
8. Constructor
1. [ ` Function() constructor ` ](/en-... | |
Mmdn_built_in_objects/Mmdn_built_in_objects_35_4.txt | [ border-block-start-style ](/en-US/docs/Web/CSS/border-block-start-style)
11. [ border-block-start-width ](/en-US/docs/Web/CSS/border-block-start-width)
12. [ border-block-style ](/en-US/docs/Web/CSS/border-block-style)
13. [ border-block-width ](/en-US/docs/Web/CSS/border-block-width)
14. [ b... | |
Mmdn_built_in_objects/4usesofjavascriptsar_220_0.txt | ## Welcome to the developer cloud | |
Mmdn_built_in_objects/Mmdn_built_in_objects_36_11.txt | JavaScript/Reference/Global_Objects/GeneratorFunction)
* [ ` AsyncGeneratorFunction ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/AsyncGeneratorFunction)
* [ ` Generator ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Generator)
* [ ` AsyncGenerator ` ](/en-US/docs/Web/JavaScript/Reference/Globa... | |
Mmdn_built_in_objects/Mmdn_built_in_objects_65_1.txt | ript/Reference/Global_Objects/Object/__lookupSetter__) Deprecated _
5. [ ` Object.assign() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign)
6. [ ` Object.create() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/create)
7. [ ` Object.defineProperties() ` ](/en-US/docs/We... | |
Mmdn_built_in_objects/Mmdn_built_in_objects_35_3.txt | /en-US/docs/Web/CSS/-webkit-overflow-scrolling) Non-standard
11. [ -webkit-tap-highlight-color ](/en-US/docs/Web/CSS/-webkit-tap-highlight-color) Non-standard
12. [ -webkit-text-fill-color ](/en-US/docs/Web/CSS/-webkit-text-fill-color)
13. [ -webkit-text-security ](/en-US/docs/Web/CSS/-webkit-text-s... | |
Mmdn_built_in_objects/Mmdn_built_in_objects_103_4.txt | late all values in an
array, one must return a new accumulator value on every iteration. This
convention propagates to JavaScript's ` reduce() ` : you should use [
spreading ](/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax) or
other copying methods where possible to create new arrays and objects as the
ac... | |
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Mmdn_built_in_objects/4usesofjavascriptsar_169_0.txt | * * * | |
Mmdn_built_in_objects/jsmapsasp_329_0.txt | ## JS Tutorial | |
Mmdn_built_in_objects/Mmdn_built_in_objects_51_3.txt | aScript/Reference/Operators/Addition)
3. [ Addition assignment (+=) ](/en-US/docs/Web/JavaScript/Reference/Operators/Addition_assignment)
4. [ Assignment (=) ](/en-US/docs/Web/JavaScript/Reference/Operators/Assignment)
5. [ async function expression ](/en-US/docs/Web/JavaScript/Reference/Operators/async_fun... | |
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4. [ Assignment (=) ](/en-US/docs/Web/JavaScript/Reference/Operators/Assignment)
5. [ async function expression ](/en-US/docs/Web/JavaScript/Reference/Operators/async_function)
6. [ async function* express... | |
Mmdn_built_in_objects/Mmdn_built_in_objects_61_1.txt | stance]() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/@@hasInstance)
2. [ ` Function.prototype.apply() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/apply)
3. [ ` Function.prototype.bind() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/bind)
4. [ ` F... | |
Mmdn_built_in_objects/Mmdn_built_in_objects_59_3.txt | cies); // "dog"
## Specifications
Specification
---
[ ECMAScript Language Specification
# sec-function-instances-prototype
](https://tc39.es/ecma262/multipage/fundamental-objects.html#sec-function-
instances-prototype)
## See also
* [ ` Function ` ](/en-US/docs/Web/JavaScript/Reference/Global_Ob... | |
Mmdn_built_in_objects/javascriptmapmethod_26_0.txt | const numbers = [1, 2, 3, 4, 5];
const doubledNumbers = numbers.map(num => num * 2);
// doubledNumbers: [2, 4, 6, 8, 10] | |
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Mmdn_built_in_objects/Mmdn_built_in_objects_105_2.txt | /Web/JavaScript/Reference/Global_Objects/String/substring)
42. [ ` String.prototype.sup() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/sup) Deprecated
43. [ ` String.prototype.toLocaleLowerCase() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toLocaleLowerCase)
44. [ ` Str... | |
Mmdn_built_in_objects/jsmapsasp_276_0.txt | #### Code Editor (Try it) | |
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Mmdn_built_in_objects/Mmdn_built_in_objects_67_4.txt | ch the source property did not exist.
js
const arrayLike = {
length: 3,
unrelated: "foo",
2: 4,
3: 33, // ignored by reverse() since length is 3
};
console.log(Array.prototype.reverse.call(arrayLike));
// { 0: 4, 3: 33, length: 3, unrelated: 'foo' }
// The index 2... | |
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43. [ ` Array.prototype.with() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/with)
6. **Inheritance**
7. **[ ` Function ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function) **
8. Constructor
1. [ ` Function() constructor ` ](/en-US/docs/We... | |
Mmdn_built_in_objects/jsmapsasp_291_0.txt | #### How To's | |
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* [ ` Array.prototype.map() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map)
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Mmdn_built_in_objects/Mmdn_built_in_objects_92_4.txt | aScript to view data.
## See also
* [ Indexed collections ](/en-US/docs/Web/JavaScript/Guide/Indexed_collections) guide
* [ ` Array ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array)
* [ ` Array.prototype.push() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/push)
* [ ` Array.prot... | |
Mmdn_built_in_objects/Mmdn_built_in_objects_21_3.txt | le number of arguments, regardless of number or type of the arguments.
## Try it
## Syntax
js
Array.of()
Array.of(element1)
Array.of(element1, element2)
Array.of(element1, element2, /* â¦, */ elementN)
### Parameters
` element1 ` , â¦, ` elementN `
Elements used to creat... | |
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Mmdn_built_in_objects/javascriptmapmethod_58_0.txt | By comparing traditional approaches with the Map method and exploring various
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Mmdn_built_in_objects/Mmdn_built_in_objects_103_6.txt | nitialValue;
for (const cur of array) {
val = update(val, cur);
}
As previously stated, the reason why people may want to use ` reduce() ` is to
mimic functional programming practices of immutable data. Therefore,
developers who uphold the immutability of the accumulator often copy the
entire accumu... | |
Mmdn_built_in_objects/322323_7_0.txt | var rating = watchList.map(e => ({
title: e.Title,
rating: e.imdbRating
})); | |
Mmdn_built_in_objects/jsmapsasp_13_0.txt | Tutorials filter input | |
Mmdn_built_in_objects/jsmapsasp_377_0.txt | // Set Map Values
fruits.set("apples", 500);
fruits.set("bananas", 300);
fruits.set("oranges", 200); | |
Mmdn_built_in_objects/Mmdn_built_in_objects_101_4.txt | n-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce)
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Mmdn_built_in_objects/Mmdn_built_in_objects_64_5.txt | pt to view data.
## See also
* [ Indexed collections ](/en-US/docs/Web/JavaScript/Guide/Indexed_collections) guide
* [ ` Array ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array)
* [ ` Array.prototype.concat() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/concat)
* [ ` Array.proto... | |
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Mmdn_built_in_objects/Mmdn_built_in_objects_104_2.txt | n-
US/docs/Web/JavaScript/Reference/Functions/get) using the [ object initializer
syntax ](/en-US/docs/Web/JavaScript/Reference/Operators/Object_initializer) or
the [ ` Object.defineProperty() ` ](/en-
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This method's behavior is only specified f... | |
Mmdn_built_in_objects/Mmdn_built_in_objects_78_2.txt |
30. [ globalThis ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/globalThis)
31. [ Infinity ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Infinity)
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Mmdn_built_in_objects/Mmdn_built_in_objects_13_9.txt | ) , [ `
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Mmdn_built_in_objects/Mmdn_built_in_objects_38_5.txt | TTP/Status/502)
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Mmdn_built_in_objects/Mmdn_built_in_objects_96_1.txt | _Objects/Object/__lookupSetter__) Deprecated
5. [ ` Object.assign() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign)
6. [ ` Object.create() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/create)
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28. [ Base64 ](/en-US/docs/Glossary/Base64)
29. [ Baseline ](/en-US/docs/Glossary/Baseline)
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31. [ Bézier curve ](/en-US/docs/Glossary/Bezier_curve)
32. [ BiDi ](/en-US/docs/Glossary/BiDi)
33. [ BigInt ](/en-US/docs/Glossary/BigInt)
34... | |
Mmdn_built_in_objects/Mmdn_built_in_objects_39_2.txt | (/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/values)
43. [ ` Array.prototype.with() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/with)
6. **Inheritance**
7. **[ ` Function ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function) **
8. Constructor
1. [ ` Function() ... | |
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