javascript 在另一个 js 文件中加载 jQuery
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load jQuery in another js file
提问by Moein Hosseini
I have a JavaScript file, which also uses jQuery in it too. To load it, I wrote this code:
我有一个 JavaScript 文件，其中也使用了 jQuery。为了加载它，我编写了以下代码：
function include(filename)
{
var head = document.getElementsByTagName('head')[0];
var script = document.createElement('script');
script.src = filename;
script.type = 'text/javascript';
head.appendChild(script)
}
include('http://ajax.googleapis.com/ajax/libs/jquery/1.7.0/jquery.min.js');
alert("1");
$(document).read(function(){});
alert("2");
This fires alert("1"), but the second alertdoesn't work. When I inspect elements, I see an error which says that $in not defined.
这会触发alert("1")，但第二个alert不起作用。当我检查元素时，我看到一个错误，指出$未定义。
How should I solve this problem?
我应该如何解决这个问题？
回答by Darin Dimitrov
You need to execute any jQuery specific code only once the script is loaded which obviously might happen at a much later point in time after appending it to the head section:
您只需要在加载脚本后执行任何特定于 jQuery 的代码，这显然可能会在将其附加到 head 部分之后的更晚的时间点发生：
function include(filename, onload) {
var head = document.getElementsByTagName('head')[0];
var script = document.createElement('script');
script.src = filename;
script.type = 'text/javascript';
script.onload = script.onreadystatechange = function() {
if (script.readyState) {
if (script.readyState === 'complete' || script.readyState === 'loaded') {
script.onreadystatechange = null;
onload();
}
}
else {
onload();
}
};
head.appendChild(script);
}
include('http://ajax.googleapis.com/ajax/libs/jquery/1.7.0/jquery.min.js', function() {
$(document).ready(function() {
alert('the DOM is ready');
});
});
And here's a live demo.
这是一个现场演示。
You may also take a look at script loaders such as yepnopeor RequireJSwhich make this task easier.
回答by Leo
The problem here is probably that, even though you include the script, it doesn't mean it is loaded when you try to do $(document).ready(function(){});. You could look into Google Loader to prevent this problem http://code.google.com/intl/fr-FR/apis/loader/
这里的问题可能是，即使您包含脚本，也不意味着它在您尝试执行$(document).ready(function(){});. 您可以查看 Google Loader 以防止出现此问题http://code.google.com/intl/fr-FR/apis/loader/
