CODEWITHSUNDEEP
javascriptjquery
rix
rix

Reputation: 10632

Problems unwatching an object using watch.js

I'm trying to use watch.js in the code below. The idea is too run watch.js in a one shot way, so it detects the boolean change (of vars.in_animation) and then unwatchs and exits. However, what happens is the code falls into inifinite loop and everytime vars.in_animation changes the watch callback is triggered and the unwatch code never runs.

I don't know whether the problem is the way I'm using watch.js, or if there is some other issue in the structure of the code. Any ideas?

base.goTo = function(targetSlide){
    if (vars.in_animation || !api.options.slideshow) 
    {            
    //arrange for a callback once in_animation is false again
    //only need to detect first change from true to false, and then unwatch
    watch(vars, "in_animation", function() 
        {
        console.log('called back, value of in_animation ' + vars.in_animation);
        unwatch(vars,"in_animation",vars.alert); //never called
        base.goTo2(vars.saved_slide);
        });  

        vars.saved_slide = targetSlide; 
        return false;
     }    
     else { base.goTo2(targetSlide); }               
     }

EDIT, just made a fiddle of the problem > http://jsfiddle.net/SZ2Ut/3/

var obj = {
name: "buddy",
alert: function(){
    alert(obj.phrase + " " + obj.name);
}

}

watch(obj, "name", function(){
alert('name has changed to: ' + obj.name);
});

//should only fire once for this one
obj.name = "johnny";
unwatch(obj, "name", obj.alert);
obj.name = "phil";

Upvotes: 0

Views: 234

Answers (1)

Bergi
Bergi

Reputation: 664385

unwatch seems to expect the watcher callback that should be removed as its third argument. Try

watch(vars, "in_animation", function callback() {
    console.log('called back, value of in_animation ' + vars.in_animation);
    unwatch(vars,"in_animation", callback);
    base.goTo2(vars.saved_slide);
});

Upvotes: 2

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