问题
Imagine some code something like this:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<HTML>
<HEAD>
<TITLE>BLAH</TITLE>
<script language='Javascript' type='text/javascript'>
var ScriptVersionReqd='1.0';
</script>
<script language='JavaScript' type='text/javascript' src='clientscript.js'></script>
etc. etc.
Does clientscript.js have access to the variable "ScriptVersionReqd"? If not, why not?
回答1:
Yes.
As long as the global variable has been put into global scope before it is called by the external script.
Edit in response to a comment: See here for a good explanation of javascript variable scope.
回答2:
Yes. You can see examples of this in things like Google Adsense. With Adsense, you first start by defining the width, colors, etc. Then you include the script which looks for those variables, and determines the output based upon those values.
<script type="text/javascript"><!--
google_ad_client = "pub-42235573";
google_ad_slot = "0774868545";
google_ad_width = 728;
google_ad_height = 90;
//-->
</script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
回答3:
Yes, there is no difference for the scope whether the script is included from a file or inline in the script tag.
来源：https://stackoverflow.com/questions/1322341/do-included-javascript-files-have-access-to-global-variables-in-the-parent-docum