数组在对象文字表示法中添加函数

Question

Here is the code I am using, not quite sure how to use literal notation yet, I have to pass the currentActiveCategories to the function somehow. Not sure if this is even the preferred way to do it, dont want to learn bad habits.

var primaryCare = {
    currentActiveCategories : [ "1", "2"],
    currentValue : addValues(this.currentActiveCategories)
}

function addValues(activeCategories) {
    tempTotal;
    for(int i = 0; i < activeCategories.length; i++){
        tempTotal += activeCategories[i];
    }
    return tempTotal;
}

Answer 1

Currently your object literal creates an object with two properties, currentActiveCategories , which is an array, and currentValue , which is set to the result of calling addValues() at the time the object literal is evaluated. You are trying to call the function with this.currentActiveCategories , which will be undefined , because this is not equal to that object at that moment.

If the idea is to have a function that can return the current total at any time you can do this:

var primaryCare = {
    currentActiveCategories : [ "1", "2"],
    currentValue : function () {
                      var tempTotal = "";
                      for(var i = 0; i < this.currentActiveCategories.length; i++){
                         tempTotal += this.currentActiveCategories[i];
                      }
                      return tempTotal;
                   }
}

primaryCare.currentValue(); // returns "12", i.e., "1" + "2"

Always declare your variables with var or they'll become globals - note that you can't declare an int in JS. You need to initialise tempTotal to an empty string before you start adding strings to it, or instead of "12" you'll get "undefined12" .

When you call a function as a method of an object, like primaryCare.currentValue() (as shown above) then within the function this will be set to that object.

It seems kind of odd to me to be adding the values as strings. If you want to use numbers and get a numeric total you can do this:

var primaryCare = {
    currentActiveCategories : [ 1, 2],   // note no quotes around the numbers
    currentValue : function () {
                      var tempTotal = 0;
                      for(var i = 0; i < this.currentActiveCategories.length; i++){
                         tempTotal += this.currentActiveCategories[i];
                      }
                      return tempTotal;
                   }
}