在javascript中获取DOM元素哈希？

Question

In case the element doesn't have an ID attribute, I want to generate some kind of unique identifier that identifies the element.

Is there some function that can get me the object hash of the DOM element object, similar to spl_object_hash in PHP ? That would be unique enough.

Answer 1

Try this :

var uid = function (i) {
    return function () { 
        return 'prefix-' + (++i); 
    };
}(0);

Usage :

uid(); // "prefix-1"
uid(); // "prefix-2"
if (!el.id) el.id = uid(); // "prefix-3"

Answer 2

There's no "object hash" in JavaScript. You can set up your own counter to create unused "id" values.

var getUnusedId = function() {
   var counter = 0;
   return function(prefix) {
     prefix = prefix || "thelolcat";
     var theId;
     while (document.getElementById(theId = prefix + counter++));
     return theId;
   };
}();

That gives you a function you can call to get an id like "thelolcat203". Each time you call it the counter is incremented, and it checks the new value to make sure there's no such element in the document.

It's not entirely safe to do that, because you don't know for sure that some content to be added dynamically won't have the same id, but it's not too hard to work with some convention that makes it pretty unlikely to have collisions. (The jQuery library does this internally anyway.)

Answer 3

That would be ridiculously taxing on the browser. What you're describing can be done using things built into JS already. Either give them ID's through JS automatically or you can select them through classes, children, parents, tag names, etc.