发表新帖
发表新帖

Defer loading of JavaScript - Uncaught ReferenceError: $ is not defined

后端 未结
关注
5 1322
鱼传尺愫
鱼传尺愫 2020-12-19 18:41

I use google code to defer loading javascript (google pages)

But I have some inline javascripts such as:
相关标签:
5条回答
  • 终归单人心
    2020-12-19 18:45

    when i want defer load jquery, i use like that:

    on header

    <script> var callBackSomething = [];</script>

    after < /body> tag

    <script defer src="//code.jquery.com/jquery.min.js"></script>
<script defer src="main.js"></script>

    in main.js

    if (typeof callBackSomething !== 'undefined' && $.isArray(callBackSomething )){
    $.each(callBackSomething , function (k, v) {
        if($.isFunction(v))
            v();
    });
}

    and in page

    let js_callback = function () {
// code jquery in here
};
callBackSomething.push(js_callback);
    0 讨论(0)
  • 無奈伤痛
    2020-12-19 18:46

    try this http://w3schools.com/jquery/default.asp. you can easily do that. 

    <script>
$(document).ready(function(){
$("p").click(function(){
alert("please work");
});
});
</script>
    0 讨论(0)
  • 悲哀的现实
    2020-12-19 18:47

    Since you are deferring loading of jquery, your inline javascript should only be called when jquery has finished loading. Use the following code, to check if the library was loaded.

    var scriptElem = document.createElement("script");

scriptElem.onload = function() {
    alert('please work');
};

scriptElem.src = "http://code.jquery.com/jquery-1.10.1.min.js";

document.getElementsByTagName("head")[0].appendChild(scriptElem);
    0 讨论(0)
  • 既然无缘
    2020-12-19 19:00

    If you are going to implement async loading of Javascripts, then it would be a better idea to not have inline Javascript which depends on the asynchronously loaded file.

    I suspect that you are loading jQuery asynchronously, i.e. after the DOM content has loaded, so any inline scripts in your DOM dependent on jQuery will fail. In that case, you may want to use something like RequireJS to manage your JS dependencies, and load them asynchronously.

    However, if you want to go for a simpler solution, I would suggest putting your JS libraries at the end of the DOM, and binding any dependencies to an onload handler.

    Something like this

    <body>
    <!-- Body content -->
    <script>document.onload = function() { //use jQuery here }</script>
</body>
<script src="/path/to/jQuery/"></script>
    0 讨论(0)
  • 一向
    2020-12-19 19:07

    You cannot use jQuery before it is loaded. If you move the <script src="jquery.js" /> at the bottom of your page you must also move all the lines that use $(...) below it.

    There is a tricky solution that goes something along these lines:

    1) Defining few variables at the top of your page:

    var _jqq = [];
var $ = function(fn) {
    _jqq.push(fn);
};

    2) In the middle of the page you can write:

    $(function() {
    alert("document ready callback #1");
});
$(function() {
    alert("document ready callback #2");
});

    3) At the bottom of your page, include jQuery:

    <script src="//code.jquery.com/jquery.min.js"></script>

    4) And finally:

    $(function() {
    $.each(_jqq, function(i, fn) {
        fn();
    });
});

    Demo

    0 讨论(0)
 看不清?
提交回复
热议问题