Array reduce in javascript (minimal example)

Do you know for cycle? Yes?! Then you know javascript Array reduce method! Let’s say you have an array with numbers e.g. [1,1,1] and you want sum of them. Then you just loop over the array and in each cycle you add next value to intermediate result (current sum).

var array = [1, 1, 1];
var current = 0;
var result;
for (var i=0, len=array.length; i<len;i++) {
current += array[i];
}
result = current;
console.log(result); // logs 3

And that’s reduce, you just loop over the array and in each iteration you take next value and add/subtract/multiply or whatever you want with intermediate result.

Well and Array already knows how to reduce. It’s its prototype method (array.prototype.reduce)

var array = [1, 1, 1];
var result;
result = array.reduce((current, next) => {
return current + next;
})
console.log(result); // logs 3

So now you know how Array reduce function works. It’s only going from a list of values to one value.

You can now go to the Mozilla Docs for Array.prototype.reduce for a more in depth overview of javascript reduce method.

Buy me a coffeeOut of coffee 😱, please help!