Question

使用$watchCollection检测更改的密钥

newValue: Object {contentType: "217", audioType: 1, wordType: 209} 
oldValue: Object {contentType: "217", audioType: 1, wordType: 210}

通常一次只会改变一个键。我想检测哪一个，以便我可以将更改保存到cookie中，而不是必须保存所有这些，即使它没有改变。

谢谢！

Answer 1

你在这里不需要$watchCollection。

只需将$watch与第三个参数一起用作true。

Answer 2

在您的情况下，您可以创建可以找到差异的filter：

app.filter('diff', function () {
  return function (objectA, objectB) {
    var propertyChanges = [];
     var objectGraphPath = ["this"];
     (function(a, b) {
        if(a.constructor == Array) {
           // BIG assumptions here: That both arrays are same length, that
           // the members of those arrays are _essentially_ the same, and 
           // that those array members are in the same order...
           for(var i = 0; i < a.length; i++) {
              objectGraphPath.push("[" + i.toString() + "]");
              arguments.callee(a[i], b[i]);
              objectGraphPath.pop();
           }
        } else if(a.constructor == Object || (a.constructor != Number && 
                  a.constructor != String && a.constructor != Date && 
                  a.constructor != RegExp && a.constructor != Function &&
                  a.constructor != Boolean)) {
           // we can safely assume that the objects have the 
           // same property lists, else why compare them?
           for(var property in a) {
              objectGraphPath.push(("." + property));
              if(a[property].constructor != Function) {
                 arguments.callee(a[property], b[property]);
              }
              objectGraphPath.pop();
           }
        } else if(a.constructor != Function) { // filter out functions
           if(a != b) {
              propertyChanges.push({ "Property": objectGraphPath.join(""), "ObjectA": a, "ObjectB": b });
           }
        }
     })(objectA, objectB);
     return propertyChanges;
  }
});

然后在$watchCollection：

中使用它

var diff = $filter('diff')(newValue, oldValue);

致How can I get a list of the differences between two JavaScript object graphs?

的信用

$ watchCollection有什么变化？

2 个答案: