Jquery在$(名称空间)的格式中提供了几个实用程序.这些方法有助于完成编程任务.一些实用方法如下所示.
$. trim()用于删除前导和尾随空格
$.trim( " lots of extra whitespace " );
$.each()用于迭代数组和对象
$.each([ "foo", "bar", "baz" ], function( idx, val ) {
console.log( "element " + idx + " is " + val );
});
$.each({ foo: "bar", baz: "bim" }, function( k, v ) {
console.log( k + " : " + v );
});可以在选择上调用.each()来迭代选择中包含的元素. .each()，而不是$ .each()，应该用于迭代选择中的元素.
$ .inArray()用于返回数组中的值索引，如果该值不在数组中，则返回-1.
var myArray = [ 1, 2, 3, 5 ];
if ( $.inArray( 4, myArray ) !== -1 ) {
console.log( "found it!" );
}$ .extend()用于更改属性使用后续对象属性的第一个对象.
var firstObject = { foo: "bar", a: "b" };
var secondObject = { foo: "baz" };
var newObject = $.extend( firstObject, secondObject );
console.log( firstObject.foo );
console.log( newObject.foo );$.proxy()用于返回一直运行的函数提供的范围 - 也就是说，将传递函数内部的含义设置为第二个参数
var myFunction = function() {
console.log( this );
};
var myObject = {
foo: "bar"
};
myFunction(); // window
var myProxyFunction = $.proxy( myFunction, myObject );
myProxyFunction();$.浏览器用于提供有关浏览器的信息
jQuery.each( jQuery.browser, function( i, val ) {
$( "<div>" + i + " : <span>" + val + "</span>" )
.appendTo( document.body );
});$.contains()用于在DOM元素提供时返回true第二个参数是第一个参数提供的DOM元素的后代，无论是直接子项还是嵌套更深.
$.contains( document.documentElement, document.body ); $.contains( document.body, document.documentElement );
$ .data()用于提供有关数据的信息
<html lang = "en">
<head>
<title>jQuery.data demo</title>
<script src = "https://code.jquery.com/jquery-1.10.2.js">
</script>
</head>
<body>
<div>
The values stored were <span></span>
and <span></span>
</div>
<script>
var div = $( "div" )[ 0 ];
jQuery.data( div, "test", {
first: 25,
last: "tutorials"
});
$( "span:first" ).text( jQuery.data( div, "test" ).first );
$( "span:last" ).text( jQuery.data( div, "test" ).last );
</script>
</body>
</html>输出如下
The values stored were 25 and tutorials
$.fn.extend()用于扩展jQuery原型
<html lang = "en">
<head>
<script src = "https://code.jquery.com/jquery-1.10.2.js">
</script>
</head>
<body>
<label><input type = "checkbox" name = "android">
Android</label>
<label><input type = "checkbox" name = "ios"> IOS</label>
<script>
jQuery.fn.extend({
check: function() {
return this.each(function() {
this.checked = true;
});
},
uncheck: function() {
return this.each(function() {
this.checked = false;
});
}
});
// Use the newly created .check() method
$( "input[type = 'checkbox']" ).check();
</script>
</body>
</html>它提供的输出如下所示 :
$ .isWindow()用于识别窗口
<!doctype html> <html lang = "en"> <head> <meta charset = "utf-8"> <title>jQuery.isWindow demo</title> <script src = "https://code.jquery.com/jquery-1.10.2.js"> </script> </head> <body> Is 'window' a window? <b></b> <script> $( "b" ).append( "" + $.isWindow( window ) ); </script> </body> </html>
It provides the output as shown below −
它返回一个表示当前时间的数字
(new Date).getTime()
$ .isXMLDoc()检查文件是否为xml
jQuery.isXMLDoc( document ) jQuery.isXMLDoc( document.body )
$ .globalEval()用于全局执行javascript
function test() {
jQuery.globalEval( "var newVar = true;" )
}
test();
$ .dequeue()用于执行队列中的下一个函数
<!doctype html>
<html lang = "en">
<head>
<meta charset = "utf-8">
<title>jQuery.dequeue demo</title>
<style>
div {
margin: 3px;
width: 50px;
position: absolute;
height: 50px;
left: 10px;
top: 30px;
background-color: green;
border-radius: 50px;
}
div.red {
background-color: blue;
}
</style>
<script src = "https://code.jquery.com/jquery-1.10.2.js"></script>
</head>
<body>
<button>Start</button>
<div></div>
<script>
$( "button" ).click(function() {
$( "div" )
.animate({ left: '+ = 400px' }, 2000 )
.animate({ top: '0px' }, 600 )
.queue(function() {
$( this ).toggleClass( "red" );
$.dequeue( this );
})
.animate({ left:'10px', top:'30px' }, 700 );
});
</script>
</body>
</html>它提供的输出如下所示 :
