Are IDs for an html element always available from the window object? [duplicate]

问题:

This question already has an answer here:

• Do DOM tree elements with ids become global variables? 4 answers

I noticed the following:

...
  

Before realizing this, I was always using the following:

var x = document.getElementById('myDiv');  x.style.color = 'red'; 

I am confused. What's the point of the second approach? Does the first approach always work?

回答1:

Are IDs for an html element always available from the window object?

No. It is a non-standard Microsoft-ism that some other browsers have adopted for compatibility reasons. It is prone to namespace collisions, and not completely cross-browser compatible: don't do it.

What's the point of the second approach?

It is standard, well-supported cross-browser (and also cross-language).

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