Dynamic Key Value Array with Multiple Values in Javascript

Question

I have:

var data = [];

I want to dynamically create string array like this:

for(var i=0; i < files.length; i++){
    data[i].part1 = "abc";
    data[i].part2 = "def";
    data[i].part3 = "ghi"; 
}

Is this possible? I tried it and it complained 'Cannot set property 'part1' of undefined'

Then I want to sort the data array by part1 values so:

data[0] = {3,a,b};
data[1] = {1,a,b};
data[2] = {5,a,b};

becomes:

data[0] = {1,a,b,c};
data[1] = {3,a,b,c};
data[2] = {5,a,b,c};

The reason I want to do this is because after the sort is done, i need to change the

data[i].part2

to something else after sorting!

melpomene · Accepted Answer · 2015-08-11 21:28:02Z

2

You could do this:

for (var i = 0; i < files.length; i++) {
    data[i] = {};
    data[i].part1 = "abc";
    data[i].part2 = "def";
    data[i].part3 = "ghi"; 
}

to set data[i] to an empty object, then fill it piece by piece. Or

for (var i = 0; i < files.length; i++) {
    data[i] = {
        part1: "abc",
        part2: "def",
        part3: "ghi"
    };
}

to set data[i] to the complete object all at once.

I don't understand the data[0] = {3,a,b}; part, though: {3,a,b} is a syntax error and it doesn't resemble your other code (which doesn't mention 3 or a or b).

But you can easily sort an array of objects by a particular property:

data.sort(function (a, b) {
    return (a.part1 > b.part1) - (a.part1 < b.part1);
});

See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort for details.

answered Aug 11, 2015 at 21:28

melpomene

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