JavaScript for loop closure issue

Question

I am adding all categories after ticking them to true if they exists in selected categories of result but it combines previous categories results with current one. I tried closure but it doesn't give me fresh object. Check out fiddle.

var allCatsResult = [{"id":1},{"id":2}, {"id":3}, ... ];

var catsArray = [1, 2] // Array of ids from allCatsResult 
var result = [
                {"id":1, selectedCategories:[{"id":1},{"id":2}]},
                {"id":2, selectedCategories:[{"id":4},{"id":5}]},
                ... 
             ];

for (var i = 0; i < results.length; i++) {
    var tmp = allCatsResult; // tried to add function form here didn't work
    for (var k = 0; k < results[i].selectedCategories.length; k++) {
        var index = catsArray.indexOf(results[i].selectedCategories[k].category_id);        
        if(index !== -1) {
            tmp[index].ticked =  true;
        }
    }               
    results[i].categories = tmp;
}

Above code gives combined result for ticked = true for all categories in each result.

should it not be results.length as that is the name of your array? — Paul Fitzgerald
– Paul Fitzgerald, Commented Apr 27, 2015 at 19:05
@webduvet : each result should have all categories but for selected categories there should be ticked = true — Shreejibawa
– Shreejibawa, Commented Apr 27, 2015 at 19:10
@charlietfl : please see fiddle result and inspect categories in each object. — Shreejibawa
– Shreejibawa, Commented Apr 27, 2015 at 19:22

Mackan · Accepted Answer · 2015-04-27 19:41:54Z

1

You need to copy/clone the array of objects, or you're manipulating the original. There are a few ways apparently. I chose the following:

var tmp = JSON.parse(JSON.stringify(allCatsResult));

This will create a new array of objects in tmp, and it will correctly only modify the clone.

edited Apr 27, 2015 at 19:41

answered Apr 27, 2015 at 19:16

Mackan

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3 Comments

charlietfl Over a year ago

why? indexOf() returns -1 if not found.

Shreejibawa Over a year ago

I never get null so I will just skip this one.

Mackan Over a year ago

@Shreejibawa I hope I can make up my past mistake with this

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