What is the difference between .concat() and .push()? Can we substitute the two?
I noticed that .concat() basically does the same thing that .push() does. Can we use the two synonymously or are there differences?
Concat is used for joining two separate arrays into one array output - it doesn't affect the original arrays if they are already assigned to a var. e.g. var nums = [1,2,3]; var nums2 = [7,8,9]; console.log(nums.concat(nums2)); // this outputs [1,2,3,7,8,9] console.log(nums) // this still outputs [1,2,3] as the above didn't alter the original var
However, when using .push the above example nests the 'joining' array into the first var nums = [1,2,3]; var nums2 = [7,8,9]; console.log(nums.push(nums2)); // outputs [1,2,3,[7,8,9]] - notice the nested array console.log(nums) // outputs [1,2,3,[7,8,9]] as the above .push() has altered the original nums variable.
Hope that makes sense.