A relatively complete summary and case of document.all_Basic knowledge

1.
document.all is a collection of all elements in the page. For example:
document.all(0) means the first element in the page
2.

Copy code Code As follows:

document.all can determine whether the browser is IE
if(document.all){
alert("is IE!");
}

3.
You can also set the id attribute (id=aaaa) to an element, and then call the element using document.all.aaaa
4.
Case:
Code 1:

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Code 2:
But often name It can be the same (for example: using checkbox to get multiple hobbies of the user)

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Code 3:
Theoretically the id in a page is Different from each other, if different tags have the same id
document.all.id will fail, like this:

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Code 4:
For a complex page (the code is very long, or the ID is automatically generated by the program), or a
program written by a JavaScript beginner, it is very likely that two tags have the same ID.
In order to avoid errors when programming, I recommend writing like this:

Copy the code The code is as follows: