Javascript access parameter inside custom sort function

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 ?

P.S: This code is inside my Ember controller class

Possible duplicate of js sort() custom function how can i pass more parameters? — C3roe
– C3roe, Commented Jan 30, 2018 at 9:23

sunil · Accepted Answer · 2018-01-30 10:23:43Z

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);

edited Jan 30, 2018 at 10:23

answered Jan 30, 2018 at 9:29

sunil

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3 Comments

sunil Over a year ago

Thanks @testndtv -- I've changed it

copenndthagen Over a year ago

Thanks a lot for that...Works like a charm now...Is it possible to customize the sort function further to support both ascending/descending based on 1 param isAscending=true/false ?

sunil Over a year ago

Sure -- you're free to change your internal sort function as much as you want. For example, you could multiply the result as follows: return s * (isAscending ? 1 : -1); where s is the value you would have returned normally.

Nina Scholz · Accepted Answer · 2018-01-30 09:33:51Z

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;
    };
},

edited Jan 30, 2018 at 9:33

answered Jan 30, 2018 at 9:26

Nina Scholz

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3 Comments

Abhishek Nair Over a year ago

Nina, can you fix the typo on line 5 b.[param] to b[param]. Apparently edits must be at least 6 characters. So I'm not able to make an edit.

copenndthagen Over a year ago

param is not available inside the closure...so a[param] & b[param] do not work

Nina Scholz Over a year ago

please add some data to the question for sorting.

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