How to check if a JavaScript array contains two specific values only [duplicate]

Question

I need to check if an array includes two values and only them.

This is my ugly solution for now:

if (myArray.includes('foo') && myArray.includes('bar') && myArray.length === 2) {
    // Do something
}

Update:

I may have to check three or more values as well. Any elegant solution? By the way, I'm using Lodash in this project.

Answer 1

I may have to check three or more values as well.

You could present your elements as an array, so if you've more than two items to check, the condition will still short and the same, using .every() method like:

myArray.every(elem => [1,2].indexOf(elem) > -1)

var myArray = [2, 1];
var myItems = [1, 2];

if (myArray.length === myItems.length && myArray.every(elem => myItems.indexOf(elem) > -1)) {
  console.log('PASS');
}

UPDATE:

Since you're using lodash, you could simply use _.difference() like:

if (_.size(myArray) === _.size(myItems) && _.difference(myArray, myItems).length === 0) {
    // Do something
}

Answer 2

That is the proper way which you have used. But to improve the comparison you can put myArray.length === 2 at the begining as if the length is not 2 it will fail immediately:

if (myArray.length === 2 && myArray.includes('foo') && myArray.includes('bar')) {
  // do something
}

If your want to compare more values then you can check that with the help of a custom function:

function checkIncluded(myArray, checkingArray){
  if(myArray.length !== checkingArray.length){
    return false;
  }
  var match = true;
  for(var i=0; i<checkingArray.length; i++){
    if(!myArray.includes(checkingArray[i])){
      match = false;
      break;
    }
  }
  return match;
}


var neededItems = ['foo', 'bar', 'pat', 'jack'];
var myArray = ['jack', 'bar', 'foo', 'pat']
var included = checkIncluded(myArray, neededItems);
if (included) {
  console.log('All items matched');
} else {
  console.log('All items do not matched');
}

neededItems = ['bar', 'pat', 'jack'];
myArray = ['jack', 'bar', 'foo', 'pat']
included = checkIncluded(myArray, neededItems);
if (included) {
  console.log('All items matched');
} else {
  console.log('All items do not matched');
}