jQuery 通用工具

$.each() $.map()

遍历列表, $.map() 可以作用于对象。

$.each([52, 97], function(index, value) { 
  alert(index + ': ' + value); 
});

$.map( [0,1,2], function(index, n){
  return n + 4;
});
//[4, 5, 6]

$.map( [0,1,2], function(n){
  return n > 0 ? n + 1 : null;
});
//[2, 3]

$.map( [0,1,2], function(n){
  return [ n, n + 1 ];
});
//[0, 1, 1, 2, 2, 3]

var dimensions = { width: 10, height: 15, length: 20 };
$.map( dimensions, function( value, key ) {
  return value * 2;
});
//[20, 30, 40] 

var dimensions = { width: 10, height: 15, length: 20 },
$.map( dimensions, function( value, key ) {
  return key;
});
//["width", "height", "length"]

$.extend()

合并对象，第一个参数表示是否进行递归深入

var object = $.extend({}, object1, object2);
var object = $.extend(true, {}, object1, object2);

$.merge()

合并列表

$.merge( [0,1,2], [2,3,4] )
//[0,1,2,2,3,4] 

$.grep()

过滤列表，第三个参数表示是否为取反

$.grep( [0,1,2], function(array,index){ return n > 0; }); //[1,2]
$.grep( [0,1,2], function(array,index){ return n > 0; }, true); //[0]

$.inArray()

存在判断

$.inArray( value, array [, fromIndex] )

$.isArray() $.isEmptyObject() $.isFunction() $.isNumeric() $.isPlainObject()$.isWindow() $.isXMLDoc()

类型判断

$.noop()

空函数

$.now()

当前时间戳，值为 (new Date).getTime()

$.parseJson() $.parseXML()

把字符串解析为对象

var xml = "<rss version='2.0'><channel><title>RSS Title</title></channel></rss>",
xmlDoc = $.parseXML( xml ),
$xml = $( xmlDoc ),
$title = $xml.find( "title" );

$.trim()

去头去尾， $.trim(str)

$.type()

判定参数的类型

# If the object is undefined or null,
#then "undefined" or "null" is returned accordingly.

* jQuery.type(undefined) === "undefined"
* jQuery.type() === "undefined"
* jQuery.type(window.notDefined) === "undefined"
* jQuery.type(null) === "null"

# If the object has an internal [[Class]] equivalent to
#one of the browser's built-in objects, the associated name is returned.
#(More details about this technique.)

* jQuery.type(true) === "boolean"
* jQuery.type(3) === "number"
* jQuery.type("test") === "string"
* jQuery.type(function(){}) === "function"
* jQuery.type([]) === "array"
* jQuery.type(new Date()) === "date"
* jQuery.type(/test/) === "regexp"

$.unique()

遍历后去重， $.unique(array)