First let’s talk about how to distinguish when the front end uses jQuery:
When jQuery issues an ajax request, it will add a piece of information named X-Requested-With to the request header. The information content is: XMLHttpRequest
You can use $_SERVER["HTTP_X_REQUESTED_WITH"] on the backend to obtain it. (Note: The dash has been replaced by an underscore, and it is not case-sensitive)
From this, we can judge whether it is an ajax request like this:
<span>//</span><span> php 判断是否为 ajax 请求 http://www.cnblogs.com/sosoft/</span> <span>if</span>(<span>isset</span>(<span>$_SERVER</span>["HTTP_X_REQUESTED_WITH"]) && <span>strtolower</span>(<span>$_SERVER</span>["HTTP_X_REQUESTED_WITH"])=="xmlhttprequest"<span>){ </span><span>//</span><span> ajax 请求的处理方式 </span> }<span>else</span><span>{ </span><span>//</span><span> 正常请求的处理方式 </span> };
When using native JavaScript to issue an ajax request, we can also add information to the header to facilitate back-end students to distinguish. The method is as follows:
<span>1</span> <span>var</span> xmlhttp=<span>new</span><span> XMLHttpRequest(); </span><span>2</span> xmlhttp.open("GET","test.php",<span>true</span><span>); </span><span>3</span> xmlhttp.setRequestHeader("X-Requested-With","XMLHttpRequest"<span>); </span><span>4</span> xmlhttp.send();
Here we also add X_REQUESTED_WITH information to the header, which is consistent with jQuery. Of course, you can also change it to other information to distinguish.
OK, what are the benefits of making the distinction? Let’s talk about two examples:
1. When the js file is not loaded, the user clicks a button or link, and what should be an ajax request becomes a normal request. Based on judgment, the backend does not output the json data during ajax, but jumps. , which is also a form of graceful degradation.
2. [A page] uses ajax to log in, [B page] uses the normal method to log in. If there is no distinction, the backend needs to write almost the same code twice, but with the distinction, the repeated code can be Eliminate.
Enable PHP pseudo-static http://www.cnblogs.com/sosoft/p/3549336.html

实现方法:1、用“$("img").delay(毫秒数).fadeOut()”语句,delay()设置延迟秒数;2、用“setTimeout(function(){ $("img").hide(); },毫秒值);”语句,通过定时器来延迟。

修改方法:1、用css()设置新样式,语法“$(元素).css("min-height","新值")”;2、用attr(),通过设置style属性来添加新样式,语法“$(元素).attr("style","min-height:新值")”。

区别:1、axios是一个异步请求框架,用于封装底层的XMLHttpRequest,而jquery是一个JavaScript库,只是顺便封装了dom操作;2、axios是基于承诺对象的,可以用承诺对象中的方法,而jquery不基于承诺对象。

增加元素的方法:1、用append(),语法“$("body").append(新元素)”,可向body内部的末尾处增加元素;2、用prepend(),语法“$("body").prepend(新元素)”,可向body内部的开始处增加元素。

在jquery中,apply()方法用于改变this指向,使用另一个对象替换当前对象,是应用某一对象的一个方法,语法为“apply(thisobj,[argarray])”;参数argarray表示的是以数组的形式进行传递。

删除方法:1、用empty(),语法“$("div").empty();”,可删除所有子节点和内容;2、用children()和remove(),语法“$("div").children().remove();”,只删除子元素,不删除内容。

去掉方法:1、用“$(selector).removeAttr("readonly")”语句删除readonly属性;2、用“$(selector).attr("readonly",false)”将readonly属性的值设置为false。

on()方法有4个参数:1、第一个参数不可省略,规定要从被选元素添加的一个或多个事件或命名空间;2、第二个参数可省略,规定元素的事件处理程序;3、第三个参数可省略,规定传递到函数的额外数据;4、第四个参数可省略,规定当事件发生时运行的函数。


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