cloning javascript event object

问题

Anybody know how to do a deep copy/cloning of a native javascript event object? I know I can create a new event object and set the appropriate properties manually to match the original event, but it'd be much easier if there's a way to just clone.

回答1:

For your purposes I'd just make it a prototype of a new object constructor and override the ones you want changed. Cloning in JS gets messy due to the circular reference issue so it may not be the quick and dirty solution you were hoping for.

function cloneEventObj(eventObj, overrideObj){

   if(!overrideObj){ overrideObj = {}; }

   function EventCloneFactory(overProps){
       for(var x in overProps){
           this[x] = overProps[x];
       }
    }

    EventCloneFactory.prototype = eventObj;

    return new EventCloneFactory(overrideObj);

}

//So add your override properties via an object
$el.click(function(e){
    var newEventObj = cloneEventObj(
        e,
        { target:document.body }
    );
    doSomething(newEventObj);
});

//or just stick 'em on manually after spitting the object out
/*...
var newEventObj = cloneEventObj(e);
newEventObj.target = document.body
...*/

In this case the 'cloned' object is the prototype object of the new object. 'this.' properties are checked for before the prototype object so these will override. Or you could just attach properties after the object is built.

回答2:

Above code will not copy any getters/setters properly. Try:

function cloneEvent(e) {
    if (e===undefined || e===null) return undefined;
    function ClonedEvent() {};  
    let clone=new ClonedEvent();
    for (let p in e) {
        let d=Object.getOwnPropertyDescriptor(e, p);
        if (d && (d.get || d.set)) Object.defineProperty(clone, p, d); else clone[p] = e[p];
    }
    Object.setPrototypeOf(clone, e);
    return clone;
}

回答3:

Inspired by Kofifus answer I just do that

function cloneEvent(type, event) {
    var evt = new Event(type);
    return Object.setPrototypeOf(evt,event);
}

来源：https://stackoverflow.com/questions/35215015/how-to-clone-a-javascript-event-object

标签

javascript

dom

dom-events