How to skip over an element in .map()?

Question

How can I skip an array element in .map?

My code:

var sources = images.map(function (img) {
    if(img.src.split(\'.\').pop() === \"json         


        

Answer 1

Here's a utility method (ES5 compatible) which only maps non null values (hides the call to reduce):

function mapNonNull(arr, cb) {
    return arr.reduce(function (accumulator, value, index, arr) {
        var result = cb.call(null, value, index, arr);
        if (result != null) {
            accumulator.push(result);
        }

        return accumulator;
    }, []);
}

var result = mapNonNull(["a", "b", "c"], function (value) {
    return value === "b" ? null : value; // exclude "b"
});

console.log(result); // ["a", "c"]

Answer 2

var sources = images.map(function (img) {
    if(img.src.split('.').pop() === "json"){ // if extension is .json
        return null; // skip
    }
    else{
        return img.src;
    }
}).filter(Boolean);

The .filter(Boolean) will filter out any falsey values in a given array, which in your case is the null.

Answer 3

Answer sans superfluous edge cases:

const thingsWithoutNulls = things.reduce((acc, thing) => {
  if (thing !== null) {
    acc.push(thing);
  }
  return acc;
}, [])

Answer 4

I use .forEach to iterate over , and push result to results array then use it, with this solution I will not loop over array twice