javascript - 使用 watch.js 取消监视对象的问题

Question

我正在尝试在下面的代码中使用watch.js。这个想法太单次运行 watch.js，所以它检测到布尔变化（vars.in_animation），然后取消观察并退出。但是，发生的情况是代码陷入无限循环，并且每次 vars.in_animation 更改时都会触发 watch 回调，并且 unwatch 代码永远不会运行。

我不知道问题是我使用 watch.js 的方式，还是代码结构中存在其他问题。有任何想法吗？

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); }               
     } 

编辑，只是解决了问题> 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";

Answer 1

unwatch似乎期望应该将其作为第三个参数删除的观察者回调。尝试

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);
});