Apply Undo Redo on elements that can dragable (drag and drop)

Question

I want to implement functionality on the svgElements that can be dragged with javascript how could I do this...

I have implemented this with mouse up

When m

Answer 1

If you're asking how to implement undo/redo functionality in general, it's fairly simple: you have an array of actions and a counter. You push new elements onto the array when actions occur and step backwards when people hit undo.

Very basic implementation:

var history = {
    stack   : [],
    counter : -1,
    add     : function(item){
        this.stack[++this.counter] = item;
        this.doSomethingWith(item);

        // delete anything forward of the counter
        this.stack.splice(this.counter+1);
    },
    undo : function(){
        this.doSomethingWith(this.stack[--this.counter]);
    },
    redo : function(){
        this.doSomethingWith(this.stack[++this.counter]);
    },
    doSomethingWith : function(item){
        // show item
    }
};

Note that there should be basic error checking to see that counter doesn't go beyond bounds and that you may want to pass 'undo' info into doSomethingWith in the case of an undo, but all that is app specific.