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Array

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Özet

JavaScript Array nesnesi, üst düzey, liste benzeri dizi yapıları için kullanılan genel bir nesnedir.

Bir dizi oluşturma

var fruits = ["Elma", "Muz"];

console.log(fruits.length);
// 2

Listedeki son elemana ulaşma

var first = fruits[0];
// Elma

var last = fruits[fruits.length - 1];
/* Diziler sıfır-tabanlı olduğu için uzunluk-1'inci eleman son elemandır.
// Muz

Loop over an Array

fruits.forEach(function (item, index, array) {
  console.log(item, index);
});
// Apple 0
// Banana 1

Dizinin sonun eleman ekleme

var newLength = fruits.push("Portakal");
// ["Elma", "Muz", "Portakal"]

Dizi sonundan eleman kaldırma

var last = fruits.pop(); // Portakal elemanını kaldır(sondan)
// ["Elma", "Muz"];

Dizi başından eleman kaldırma

var first = fruits.shift(); // Elma elemanını kaldır(baştan)
// ["Muz"];

Dizi başına eleman ekleme

var newLength = fruits.unshift("Çilek") // Başa ekle
// ["Çilek", "Muz"];

Diziden istenilen sıradaki elemanı bulma

fruits.push("Mango");
// ["Çilek", "Muz", "Mango"]

var pos = fruits.indexOf("Muz");
// 1

Belirli bir sıradaki elemanı silme

var removedItem = fruits.splice(pos, 1); // bir elemanı kaldırma
// ["Çilek", "Mango"]

Dizi kopyalama

var shallowCopy = fruits.slice(); //
// ["Çilek", "Mango"]

Söz Dizimi

[element0, element1, ..., elementN]
new Array(element0, element1, ..., elementN)
new Array(diziUzunlugu)

Not: N + 1 = dizi uzunluğu

element0, element1, ..., elementN: Bir dizi new Array() nesnesine verilen argüman dışında(yukarıdaki diziUzunluğu argümanı gibi), verilen elemanlar ile oluşturulabilir.(Yukarıda görüldüğü üzere) Bu özel durum sadece new Array() nesnesiyle (Array Constructor) oluşturulan dizilere uygulanabilir, köşeli parantezler ( [ ve ] ) ile oluşturulan dizilere uygulanamaz.
arrayLength (dizi uzunluğu): array nesnesinden sadece 0 ve 2³²-1 (dahil) arasındaki tam sayılardan biri argüman olarak geçirilebilir.; If the only argument passed to the Array constructor is an integer between 0 and 2³²-1 (inclusive), a new, empty JavaScript array and its length is set to that number. If the argument is any other number, a RangeError exception is thrown.

Tanım

Arrays are list-like objects that come with a several built-in methods to perform traversal and mutation operations. Neither the size of a JavaScript array nor the types of its elements are fixed. Since an array's size can grow or shrink at any time, JavaScript arrays are not guaranteed to be dense. In general, these are convenient characteristics; but if these features are not desirable for your particular use case, you might consider using WebGL typed arrays.

Note that you shouldn't use an array as an associative array. You can use plain objects instead, although doing so comes with its own caveats. See the post Lightweight JavaScript dictionaries with arbitrary keys as an example.

Dizi nesnelerine erişme

JS dizileri sıfır-tabanlı'dır. Yani ilk elemanın dizideki index'i 0'dır. Son elemanın index'i length değerinin bir eksiğine eşittir.

var arr = ["bu ilk eleman", "bu ikinci eleman"];
console.log(arr[0]);              // ilk elemanı yazdırır
console.log(arr[1]);              // ikinci elemanı yazdırır
console.log(arr[arr.length - 1]); // son elemanı yazdırır

Array elements are just object properties, in the way that toString is a property. However, note that trying to access the first element of an array as follows will throw a syntax error:

console.log(arr.0); // a syntax error

Note that there is nothing unique about JavaScript arrays and their properties that causes this. JavaScript properties that begin with a digit cannot be referenced with dot notation. They must be accessed using bracket notation. For example, if you had an object with a property "3d", it too would have to be referenced using bracket notation, not dot notation. This similarity is exhibited in the following two code samples:

var years = [1950, 1960, 1970, 1980, 1990, 2000, 2010];
console.log(years.0);   // a syntax error
console.log(years[0]);  // works propertly

renderer.3d.setTexture(model, "character.png");     // a syntax error
renderer["3d"].setTexture(model, "character.png");  // works properly

Note that in the 3d example, "3d" had to be quoted. It's possible to quote the JavaScript array indexes as well (e.g., years["2"] instead of years[2]), although it's not necessary. The 2 in years[2] eventually gets coerced into a string by the JavaScript engine, anyway, through an implicit toString conversion. It is for this reason that "2" and "02" would refer to two different slots on the years object and the following example logs true:

console.log(years["2"] != years["02"]);

Similarly, object properties which happen to be reserved words(!) can only be accessed as string literals in bracket notation:

var promise = {
  'var'  : 'text',
  'array': [1, 2, 3, 4]
};

console.log(promise['array']);

Relationship between `length` and numerical properties

A JavaScript array's length property and numerical properties are connected. Several of the built-in array methods (e.g., join, slice, indexOf, etc.) take into account the value of an array's length property when they're called. Other methods (e.g., push, splice, etc.) also result in updates to an array's length property.

var fruits = [];
fruits.push("banana", "apple", "peach");

console.log(fruits.length); // 3

When setting a property on a JavaScript array when the property is a valid array index and that index is outside the current bounds of the array, the array will grow to a size large enough to accommodate an element at that index, and the engine will update the array's length property accordingly:

fruits[3] = "mango";
console.log(fruits[3]);
console.log(fruits.length); // 4

Setting the length property, directly, also results in special behavior.

fruits.length = 10;
console.log(fruits);        // The array gets padded with undefined
console.log(fruits.length); // 10

This is explained further on the Array.length page.

Creating an array using the result of a match

The result of a match between a regular expression and a string can create a JavaScript array. This array has properties and elements which provide information about the match. Such an array is returned by RegExp.exec, String.match, and String.replace. To help explain these properties and elements, look at the following example and then refer to the table below:

// Match one d followed by one or more b's followed by one d
// Remember matched b's and the following d
// Ignore case

var myRe = /d(b+)(d)/i;
var myArray = myRe.exec("cdbBdbsbz");

The properties and elements returned from this match are as follows:

Property/Element	Description	Example
`input`	A read-only property that reflects the original string against which the regular expression was matched.	cdbBdbsbz
`index`	A read-only property that is the zero-based index of the match in the string.	1
`[0]`	A read-only element that specifies the last matched characters.	dbBd
`[1], ...[n]`	Read-only elements that specify the parenthesized substring matches, if included in the regular expression. The number of possible parenthesized substrings is unlimited.	[1]: bB [2]: d

Properties

For properties available on Array instances, see Properties of Array instances.

Array.length: The Array constructor's length property whose value is 1.
Array.prototype: Allows the addition of properties to all array objects.

Methods

For methods available on Array instances, see Methods of Array instances.

Array.from(): Creates a new Array instance from an array-like or iterable object.
Array.isArray(): Returns true if a variable is an array, if not false.
Array.observe(): Asynchronously observes changes to Arrays, similar to Object.observe() for objects. It provides a stream of changes in order of occurrence.
Array.of(): Creates a new Array instance with a variable number of arguments, regardless of number or type of the arguments.

`Array` instances

All Array instances inherit from Array.prototype. The prototype object of the Array constructor can be modified to affect all Array instances.

Properties

Array.prototype.constructor: Specifies the function that creates an object's prototype.
Array.prototype.length: Reflects the number of elements in an array.

Methods

Mutator methods

These methods modify the array:

Array.prototype.copyWithin(): Copies a sequence of array elements within the array.
Array.prototype.fill(): Fills all the elements of an array from a start index to an end index with a static value.
Array.prototype.pop(): Removes the last element from an array and returns that element.
Array.prototype.push(): Adds one or more elements to the end of an array and returns the new length of the array.
Array.prototype.reverse(): Reverses the order of the elements of an array in place — the first becomes the last, and the last becomes the first.
Array.prototype.shift(): Removes the first element from an array and returns that element.
Array.prototype.sort(): Sorts the elements of an array in place and returns the array.
Array.prototype.splice(): Adds and/or removes elements from an array.
Array.prototype.unshift(): Adds one or more elements to the front of an array and returns the new length of the array.

Accessor methods

These methods do not modify the array and return some representation of the array.

Array.prototype.concat(): Returns a new array comprised of this array joined with other array(s) and/or value(s).
Array.prototype.includes(): Determines whether an array contains a certain element, returning true or false as appropriate.
Array.prototype.join(): Joins all elements of an array into a string.
Array.prototype.slice(): Extracts a section of an array and returns a new array.
Array.prototype.toSource(): Returns an array literal representing the specified array; you can use this value to create a new array. Overrides the Object.prototype.toSource() method.
Array.prototype.toString(): Returns a string representing the array and its elements. Overrides the Object.prototype.toString() method.
Array.prototype.toLocaleString(): Returns a localized string representing the array and its elements. Overrides the Object.prototype.toLocaleString() method.
Array.prototype.indexOf(): Returns the first (least) index of an element within the array equal to the specified value, or -1 if none is found.
Array.prototype.lastIndexOf(): Returns the last (greatest) index of an element within the array equal to the specified value, or -1 if none is found.

Iteration methods

Several methods take as arguments functions to be called back while processing the array. When these methods are called, the length of the array is sampled, and any element added beyond this length from within the callback is not visited. Other changes to the array (setting the value of or deleting an element) may affect the results of the operation if the method visits the changed element afterwards. While the specific behavior of these methods in such cases is well-defined, you should not rely upon it so as not to confuse others who might read your code. If you must mutate the array, copy into a new array instead.

Array.prototype.forEach(): Calls a function for each element in the array.
Array.prototype.entries(): Returns a new Array Iterator object that contains the key/value pairs for each index in the array.
Array.prototype.every(): Returns true if every element in this array satisfies the provided testing function.
Array.prototype.some(): Returns true if at least one element in this array satisfies the provided testing function.
Array.prototype.filter(): Creates a new array with all of the elements of this array for which the provided filtering function returns true.
Array.prototype.find(): Returns the found value in the array, if an element in the array satisfies the provided testing function or undefined if not found.
Array.prototype.findIndex(): Returns the found index in the array, if an element in the array satisfies the provided testing function or -1 if not found.
Array.prototype.keys(): Returns a new Array Iterator that contains the keys for each index in the array.
Array.prototype.map(): Creates a new array with the results of calling a provided function on every element in this array.
Array.prototype.reduce(): Apply a function against an accumulator and each value of the array (from left-to-right) as to reduce it to a single value.
Array.prototype.reduceRight(): Apply a function against an accumulator and each value of the array (from right-to-left) as to reduce it to a single value.
Array.prototype.values(): Returns a new Array Iterator object that contains the values for each index in the array.
Array.prototype[@@iterator](): Returns a new Array Iterator object that contains the values for each index in the array.

`Array` generic methods

Sometimes you would like to apply array methods to strings or other array-like objects (such as function arguments). By doing this, you treat a string as an array of characters (or otherwise treat a non-array as an array). For example, in order to check that every character in the variable str is a letter, you would write:

function isLetter(character) {
  return (character >= "a" && character <= "z");
}

if (Array.prototype.every.call(str, isLetter))
  alert("The string '" + str + "' contains only letters!");

This notation is rather wasteful and JavaScript 1.6 introduced a generic shorthand:

if (Array.every(isLetter, str))
  alert("The string '" + str + "' contains only letters!");

Generics are also available on String.

These are currently not part of ECMAScript standards (though the ES6 Array.from() can be used to achieve this). The following is a shim to allow its use in all browsers:

// Assumes Array extras already present (one may use polyfills for these as well)
(function () {
    'use strict';

    var i,
        // We could also build the array of methods with the following, but the
        //   getOwnPropertyNames() method is non-shimable:
        // Object.getOwnPropertyNames(Array).filter(function (methodName) {return typeof Array[methodName] === 'function'});
        methods = [
            'join', 'reverse', 'sort', 'push', 'pop', 'shift', 'unshift',
            'splice', 'concat', 'slice', 'indexOf', 'lastIndexOf',
            'forEach', 'map', 'reduce', 'reduceRight', 'filter',
            'some', 'every', 'isArray'
        ],
        methodCount = methods.length,
        assignArrayGeneric = function (methodName) {
            var method = Array.prototype[methodName];
            Array[methodName] = function (arg1) {
                return method.apply(arg1, Array.prototype.slice.call(arguments, 1));
            };
        };

    for (i = 0; i < methodCount; i++) {
        assignArrayGeneric(methods[i]);
    }
}());

Örnekler

Bir dizi oluşturmak

The following example creates an array, msgArray, with a length of 0, then assigns values to msgArray[0] and msgArray[99], changing the length of the array to 100.

var msgArray = new Array();
msgArray[0] = "Hello";
msgArray[99] = "world";

if (msgArray.length == 100)
   print("The length is 100.");

Creating a two-dimensional array

The following creates chess board as a two dimensional array of strings. The first move is made by copying the 'p' in 6,4 to 4,4. The old position 6,4 is made blank.

var board = 
[ ['R','N','B','Q','K','B','N','R'],
  ['P','P','P','P','P','P','P','P'],
  [' ',' ',' ',' ',' ',' ',' ',' '],
  [' ',' ',' ',' ',' ',' ',' ',' '],
  [' ',' ',' ',' ',' ',' ',' ',' '],
  [' ',' ',' ',' ',' ',' ',' ',' '],
  ['p','p','p','p','p','p','p','p'],
  ['r','n','b','q','k','b','n','r']];
print(board.join('\n') + '\n\n');

// Move King's Pawn forward 2
board[4][4] = board[6][4];
board[6][4] = ' ';
print(board.join('\n'));

Sonu

R,N,B,Q,K,B,N,R
P,P,P,P,P,P,P,P
 , , , , , , , 
 , , , , , , , 
 , , , , , , , 
 , , , , , , , 
p,p,p,p,p,p,p,p
r,n,b,q,k,b,n,r

R,N,B,Q,K,B,N,R
P,P,P,P,P,P,P,P
 , , , , , , , 
 , , , , , , , 
 , , , ,p, , , 
 , , , , , , , 
p,p,p,p, ,p,p,p
r,n,b,q,k,b,n,r

Feature	Chrome	Firefox (Gecko)	Internet Explorer	Opera	Safari (WebKit)
Basic support	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)

Feature	Android	Firefox Mobile (Gecko)	IE Phone	Opera Mobile	Safari Mobile
Basic support	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)

Daha fazlası

Document Tags and Contributors

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Contributors to this page: pasalog, teoli, ramesaliyev

Last updated by: pasalog, 18 Ara 2015 10:44:27

Array

Özet

Söz Dizimi

Tanım

Dizi nesnelerine erişme

Relationship between length and numerical properties

Creating an array using the result of a match

Properties

Methods

Array instances

Properties

Methods

Mutator methods

Accessor methods

Iteration methods

Array generic methods

Örnekler

Bir dizi oluşturmak

Creating a two-dimensional array

Tarayıcı Uyumluluk Tablosu

Daha fazlası

Document Tags and Contributors

Relationship between `length` and numerical properties

`Array` instances

`Array` generic methods