自定义排序函数中的Javascript访问参数

Question

I have a custom sort function defined & call it as below;

myArr.sort(this.sortArrayBy, key);

sortArrayBy: function(a, b) {

    let param = this.get('sortKey'); //How do I get this value here ? cannot pass it as param OR even access via 'this'

    if (a.param < b.param)
        return -1;
    if (a.param > b.param)
        return 1;
    return 0;
},

I want to pass an additional param inside that function. How do I get access to that class attribute ?

PS: This code is inside my Ember controller class

Answer 1

You could use a closure over the wanted sort key.

myArr.sort(this.sortArrayBy(key));

sortArrayBy: function (param) {
    return function(a, b) {
        if (a[param] < b[param])
            return -1;
        if (a[param] > b[param])
            return 1;
        return 0;
    };
},

Answer 2

You can't make this .sort() take an extra parameter. A workaround is to create a function which wraps a custom defined sort function which does take the additional parameter.

---

You can define your own sort function which takes an extra parameter:

sortArrayBy: function(a, b, param) {
    // ... sort logic here ...
    return 0;
}

Then, at the point you call myArr.sort , you can define a wrapper to this function which only takes the expected two parameters:

var self = this;
var sortFunc = function(a, b) {
    return self.sortArrayBy(a, b, self.get('sortKey'));  
};
myArr.sort(sortFunc, key);