js get element by id

HI all! I have a doubt. I need to get an element via its id. I know i can use document.getElementById() or jquery selector, but i don´t want to use jquery or any other library. The idea is to build a component using just js and no libraries.

I got this situation, code generated by code:

<div id="objprop">

    <div id="prop-header"><span>Mi Ventana</span></div>
    <div id="prop_width" style="clear: both;">
        <label style="margin-left: 7px; margin-bottom: 7px; float: left;">Width</label>
        <input type="text" style="float: right; margin-right: 7px; width: 70px;" id="width">
    </div>
    <div id="prop_height" style="clear: both;">
        <label style="margin-left: 7px; margin-bottom: 7px; float: left;">Height</label>
        <input type="text" style="float: right; margin-right: 7px; width: 70px;" id="height">
    </div>
    <div id="prop_left" style="clear: both;">
        <label style="margin-left: 7px; margin-bottom: 7px; float: left;">Left</labe开发者_开发技巧l>
        <input type="text" style="float: right; margin-right: 7px; width: 70px;" id="left">
    </div>
    <div id="prop_top" style="clear: both;">
        <label style="margin-left: 7px; margin-bottom: 7px; float: left;">Top</label>
        <input type="text" style="float: right; margin-right: 7px; width: 70px;" id="top">
    </div>
</div>

so, let supose i want to set the value of input width id with. I´m not sure about using document.getElementById because may be other elements with same id in the html.

well that is my doubt

The HTML specification states that an id must only be used once. It must be unique through-out a document. If you're dealing with valid documents, you should feel comfortable using document.getElementById()

According to the specifications the id attribute of an element must be unique in a document. So as long as the document conforms to the specs you should have no problem using getElementById().

The values of "id" attributes must be unique throughout the page. You're right that it would be a problem for "getElementById()" to have to deal with the same "id" value being used on multiple elements; that's why you absolutely should not do that. That's why it's called an "id" — it is the identifier for the element.

I´m not sure about using document.getElementById because may be other elements with same id in the html.

Id MUST be unique.

http://validator.w3.org/

thanks.

To solve my problem. i did the follow:

I create elements dynamic so i added a post fix like this: this.postfix = new Date().getTime();

so, when i have to add and input with id 'width' i add the postfix like it is named 'width_'+postfix. so i can use in a secure way document.getElementById;

Thanks