How to stop looping once it found?

Question

If three is found then it should return true and stop the iteration. Otherwise return return false if not found.

I am using filter() - is it wrong approach to use?

var data = [
  'one',
  'two',
  'three',
  'four',
  'three',
  'five',
];

found = data.filter(function(x) {
   console.log(x);
   return x == "three";
});

console.log(found);

Demo: https://jsbin.com/dimolimayi/edit?js,console

Answer 1

You can use array#some at this context,

var data = [
  'one',
  'two',
  'three',
  'four',
  'three',
  'five',
];

found = data.some(function(x) {
   return x == "three";
});

console.log(found); // true or false

If you use filter, then the array will be filtered based on the truthy value returned inside of the callBack function. So if any matches found meaning, if the function returned with value true, then the element on that particular iteration will be collected in an array and finally the array will be returned.

Hence in your case ["three", "theree"] will be returned as a result. If you dont have any "three", then an empty array would be returned, At this context you have to make a additional check to find the truthy value as a result.

For Example:

var res = arr.filter(itm => someCondition);
var res = !!res.length;
console.log(res); //true or false.

So to avoid that over killing situation we are using Array#some.