no-cache script without using Jquery

问题

Hello I am trying to create a script which inserts into any webpage a meta tag to force no-cache.

Currently this is my code and I dont want to use Jquery (as shown in Script to force IE8 cache behaviour).

var MAXlen = document.getElementsByTagName('head')[0].childNodes.length; 
//Get the length of childnodes of head.

while(MAXlen--)
{
 document.getElementsByTagName('head')[0].childNodes[MAXlen+1] = document.getElementsByTagName('head')[0].childNodes[MAXlen]; 
//store every node one place after.

 if(MAXlen == 0)
 document.getElementsByTagName('head')[0].childNodes[0].innerHTML = '<META HTTP-EQUIV="Pragma" CONTENT="no-cache">';
 //place this hmtlcode into the first element of head.
 break;
}

回答1:

I would use ... prepend without JQuery:

parent.insertBefore(child, parent.firstChild);

parentNode.insertBefore(newChild, refChild);

Inserts the node newChild as a child of parentNode before the existing child node refChild. (Returns newChild.)

If refChild is null, newChild is added at the end of the list of children. Equivalently, and more readably, use parentNode.appendChild(newChild).

In this case, you wouldn't need to loop through as in the code you presented.

UPDATE:

Try this with your code ...

var meta = document.createElement('meta');
meta.httpEquiv = "Pragma";
meta.content = "no-cache";
var head = document.getElementsByTagName('head')[0]
head.insertBefore(meta, head.firstChild);

1. First, build the meta tag as a node.
2. Then, capture the head tag as a variable.
3. Using the variable, insert the node before the first child.

COMMENTS:

• Tested functional in Chrome.
• Tested functional in IE8 with console warning: "The code on this page disabled back and forward caching"

来源：https://stackoverflow.com/questions/27732140/no-cache-script-without-using-jquery