I'm trying to add the values of two arrays in javascript eg. [1,2,1] + [3,2,3,4]
The answer should be 4,4,4,4 but I'm either getting 4,4,4 or 4,4,4,NaN if I change the 1st array length to 4.
I know a 4th number needs to be in the 1st array, but i can't figure out how to tell javascript to make it 0 rather then undefined if there is no number.
Use isNaN to ensure the value does not evaluate to NaN in arithmetic operations.
This will safely add two numbers such that if one of them is not a number, it will be substituted with 0.
var c = (isNaN(a) ? 0 : a) + (isNaN(b) ? 0 : b);
If you suspect that either a or b could be a string instead of number ("2" instead of 2), you have to convert it into number before adding it. You can use a Unary + to do it.
var c = (isNaN(a) ? 0 : +a) + (isNaN(b) ? 0 : +b);
(array1[3] || 0) + (array2[3] || 0)
var a = [ 1, 2, 3, 4, 5 ];
var b = [ 2 , 3];
var c = [];
var maxi = Math.max(a.length, b.length);
for (var i = 0; i < maxi; i++) {
c.push( (a[i] || 0) + (b[i] || 0) );
}
[1,2,3] + [3,2,1]
In the above example, JavaScript converts the arrays to strings anyway so the result is:
1,2,33,2,1
