jQuery.each()
Categories: Utilities
jQuery.each( collection, callback(indexInArray, valueOfElement) )Returns: Object
Description: A generic iterator function, which can be used to seamlessly iterate over both objects and arrays. Arrays and array-like objects with a length property (such as a function's arguments object) are iterated by numeric index, from 0 to length-1. Other objects are iterated via their named properties.
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jQuery.each( collection, callback(indexInArray, valueOfElement) )
version added: 1.0collection The object or array to iterate over.
callback(indexInArray, valueOfElement) The function that will be executed on every object.
The $.each()
function is not the same as $(selector).each(), which is used to iterate, exclusively, over a jQuery object. The $.each()
function can be used to iterate over any collection, whether it is a map (JavaScript object) or an array. In the case of an array, the callback is passed an array index and a corresponding array value each time. (The value can also be accessed through the this
keyword, but Javascript will always wrap the this
value as an Object
even if it is a simple string or number value.) The method returns its first argument, the object that was iterated.
$.each([52, 97], function(index, value) { alert(index + ': ' + value); });
This produces two messages:
0: 52
1: 97
If a map is used as the collection, the callback is passed a key-value pair each time:
var map = { 'flammable': 'inflammable', 'duh': 'no duh' }; $.each(map, function(key, value) { alert(key + ': ' + value); });
Once again, this produces two messages:
flammable: inflammable
duh: no duh
We can break the $.each()
loop at a particular iteration by making the callback function return false
. Returning non-false is the same as a continue
statement in a for loop; it will skip immediately to the next iteration.
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Iterates through the array displaying each number as both a word and numeral
HTML:
<div id="one"></div> <div id="two"></div> <div id="three"></div> <div id="four"></div> <div id="five"></div>
CSS:
div { color:blue; } div#five { color:red; }
Code:
var arr = [ "one", "two", "three", "four", "five" ]; var obj = { one:1, two:2, three:3, four:4, five:5 }; jQuery.each(arr, function() { $("#" + this).text("Mine is " + this + "."); return (this != "three"); // will stop running after "three" }); jQuery.each(obj, function(i, val) { $("#" + i).append(document.createTextNode(" - " + val)); });
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Iterates over items in an array, accessing both the current item and its index.
Code:
$.each( ['a','b','c'], function(i, l){ alert( "Index #" + i + ": " + l ); });
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Iterates over the properties in an object, accessing both the current item and its key.
Code:
$.each( { name: "John", lang: "JS" }, function(k, v){ alert( "Key: " + k + ", Value: " + v ); });
jQuery.each( collection, [ overwrite ], callback(indexInArray, valueOfElement) )Returns: Object
Plugin: jQuery.each
Description: A generic iterator function, which can be used to seamlessly iterate over both objects and arrays. Arrays and array-like objects with a length property (such as a function's arguments object) are iterated by numeric index, from 0 to length-1. Other objects are iterated via their named properties.
-
jQuery.each( collection, [ overwrite ], callback(indexInArray, valueOfElement) )
version added: 1.0collection The object or array to iterate over.
overwrite A boolean indication whether to overwrite every object by the return value.
callback(indexInArray, valueOfElement) The function that will be executed on every object.
The $.each()
function is not the same as .each()
, which is used to iterate, exclusively, over a
jQuery object. The $.each()
function can be used to iterate over any collection, whether it is a map
(JavaScript object) or an array. In the case of an array, the callback is passed an array index and a
corresponding array value each time. (The value can also be accessed through the this keyword, but
Javascript will always wrap the this
value as an Object even if it is a simple string or number value.)
The method returns its first argument, the object that was iterated.
We can break the $.each()
loop at a particular iteration by making the callback function return false.
Returning non-false is the same as a continue statement in a for loop; it will skip immediately to the next
iteration.
If we set the overwrite argument, returning non-false and non-undefined will set a new value to current item.
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Iterates over the properties in an object, accessing both the current item and its key.
Code:
$.each( { a: 0, b: 1, c: 2, d: 3, e: 4 }, true, function(key, value){ alert( "Key: " + key + ", Value: " + value ); return value >= 2 ? value+1 : false; });
Results:
{ a: 1, b: 2, c: 3, d: 3, e: 4 }