Changing the content of meta refresh does not change refreshing time

问题

I have a meta http-equiv="refresh" inside the <head>.

<head>
     <meta name="mymeta" http-equiv="refresh" content="2" id="myMeta">
</head>

Using Javascript, I'm trying to change the content attribute of this meta tag.

var myMeta = document.getElementById("myMeta");
myMeta.content="10";

When I display the content via document.write(myMeta.content);, I get the changed value which is 10, however, the meta tag will keep refreshing each 2 seconds.

I have tested this both in Firefox and Opera.

FULL PAGE

<!DOCTYPE html>
<html>
<head>
<meta name="mymeta" http-equiv="refresh" content="2" id="myMeta">
<script>
var myMeta=document.getElementById("myMeta");
myMeta.content="10";
document.write(myMeta.content);
</script>
</head>
<body>
</body>
</html>

回答1:

This happens because the browser immediately process the <meta> tag when it is present onload.

See DEMO.

When the document is being loaded, the browser sees and processes the following:

<meta name="mymeta" http-equiv="refresh" content="2" id="myMeta"/>

Even though you try to change its content from 2 to 10, that 2 second refresh is already acknowledged and the browser waits for 2 seconds before it refreshes the page. The 10-second refresh that is injected by JavaScript actually works*, although the page has been refreshed by the time it reaches 2 seconds and nothing seems to happen. This process is then repeated again and again.

Try the opposite and see what happens.

^{*This only works on Safari and Chrome. Firefox and Opera does not support the modification of meta refresh through JavaScript.}

回答2:

The getElementsByTagName method returns a NodeList so you need to specify an index to correctly access the element:

 var myMeta = document.getElementsByTagName("meta")[0];

As someone mentioned this will probably still not work as the meta tag will need to be re-appended to have the desired effect.

Since you're using JavaScript you can just use setTimeout to achieve the same behavior

setTimeout(function() {
    location.reload();
},2000); // reload page after 2 seconds

来源：https://stackoverflow.com/questions/14790065/changing-the-content-of-meta-refresh-does-not-change-refreshing-time

标签

javascript

html

meta-tags