document.write inside for loops
Question
I have the following HTML document
<html>
<script>
function explode() {
pp = document.getElementsByTagName("a");
for(i=0;i<pp.length;i++) {
document.write(pp[i].href);
}
}
</script>
<body>
<a href="http://google.com">Google</a>
<a href="http://yahoo.com">Yahoo</a>
<button onclick="explode()">Explode</button>
<body>
</html>
When executed I expect all the hyperlinks printed on my window, but I get only the first one. Can someone explain this
Update I am convinced by the answer that document.write will reset the page contents, but if it is that so then, I already the list of objects in the variable pp and by the end of the for loop I should get the LAST element, why the first element ?
3 answers
solution1
2 2014-03-09 15:05:28
document.write - will clear your browser at first time when he meets document.write !
You have to aggregate the values.
Do this
function explode() {
pp = document.getElementsByTagName("a");
var a='';
for(i=0;i<pp.length;i++) {
a+=pp[i].href
}
document.write(a);
}
http://jsbin.com/buzexuce/2/edit
To illustrate on the other direction :
look what happens here :
<a href="http://google.com">Google</a>
<a href="http://yahoo.com">Yahoo</a>
<button onclick="explode()">Explode</button>
<script>
var pp = document.getElementsByTagName("a");
for(i=0;i<pp.length;i++)
{ document.write(i);}
</script>
(before dom ready - everything is fine as expected).
solution2
2 ACCPTED 2014-03-09 15:08:32
If you start writing to the document after it has been completely loaded, you will implicitly open a new document and replace the current document. You can use document.write to add to the document while it is loading (ie in scripts tags inline in the code), but once the document is complete, using document.write will implicitly call document.open to create a new document to write to.
The list of elements that you get from the getElementByTagName method returns a live list, which is updated when elements are added to or removed from the DOM. When you have written the first item to the document the list is empty, as there aren't any matching elements in the document any more.
solution3
0 2014-03-09 15:04:05
它应该是：
document.write(pp[i].href);
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