JS.findElementById() usage introduction_javascript skills

Copy code The code is as follows:

his.findElementById = function (identifier, frame) {
if (!frame) {
frame = window;
}

var element = frame.document.getElementById(identifier);
if (element && element.getAttribute('id') = == identifier) ​​{
return element;
}
// else if (browserVersion.isIE || browserVersion.isOpera) {
// // SEL-484
// var xpath = '/descendant::*[@id=' identifier.quoteForXPath() ']';
// return this
// .findElementByXPath(xpath);
// }
else {
// MOD 2011-12-9 Some new windows have the same frame as the old window. Generally, the new window is operated first. Find from back to front
if (frame.frames && frame.frames.length > 0) {
for (var i = frame.frames.length - 1; i >= 0; i--) {
element = this.findElementById(identifier, frame.frames[i]); //frames[i].document.getElementById(identifier);
if (element && element.getAttribute("id") = == identifier) ​​{
return element;
}
}
}
}
return null;
};