CODEWITHSUNDEEP
javascripthighcharts
WindowsMaker
WindowsMaker

Reputation: 3400

Building sparse array

I have a big array (say 500 entries) but most of the values are Null. How can i represent the array instead of having [null, null ... 3, null, null, ...]?

the array is passed to highcharts for plotting. Highcharts plots a point for every element in the array so I really don't need those nulls.

Upvotes: 2

Views: 156

Answers (1)

Mark Reed
Mark Reed

Reputation: 95252

If you set array[200] to something, it's not like JavaScript comes along behind you and sets array[0] through array[199]. Arrays are automatically sparse.

So is the problem that if you ask for an uninitialized element, you get undefined back instead of null? Or is there some other issue?

If it's the undefined vs null thing, then just add the nulls after you initialize it, with a loop, instead of having to put them in the big literal blob:

for (var i=0; i<array.length; ++i) { 
    if (typeof(array[i]) === 'undefined') { 
        array[i] = null; 
    } 
}

If you want nulls out past what you initialized, replace array.length with whatever your maximum index needs to be (+1, or else change the < to <=).

Upvotes: 4

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