Document. getElementBy (& quot; id & quot;) and $ (& quot; # I

The following is a brief introduction:

The first method is to get the object in js. It is more direct. If a page has multiple IDs, such a long document. getElementBy ("id") must be written each time ")

Copy codeThe Code is as follows:
Document. getElementBy ("id ")


Document. getElementById

For personal comparison, we recommend that you use prototype to define document. getElementById:

Copy codeThe Code is as follows:
Function $ ()
{
Var elements = new Array ();
For (var I = 0; I <arguments. length; I ++)
{
Var element = arguments [I];
If (typeof element = 'string ')
Element = document. getElementById (element );
If (arguments. length = 1)
Return element;
Elements. push (element );
}
Return elements;
}

You can also define it using the following code:

Copy codeThe Code is as follows:
Function $ (objectId ){
If (document. getElementById & document. getElementById (objectId )){
Return document. getElementById (objectId); // W3C DOM
} Else if (document. all & document. all (objectId )){
Return document. all (objectId); // MSIE 4 DOM
} Else if (document. layers & document. layers [objectId]) {
Return document. layers [objectId]; // NN 4 DOM .. note: this won't find nested layers
} Else {
Return false;
}
}


The second method is to obtain the id in jquery.

For details, refer to this article.

Http://www.jb51.net/article/27617.htm

Http://www.jb51.net/article/26702.htm