I try to compare a split up string with multiple characters

Question

var input = 'HISFANTOR';
var output = [];
var char = input.split('');

for (var i = 0, len = char.length; i < len; i++) {
   if (char[i] == 'H' || 'K' || 'Y' || 'V' || 'B' || 'C' || 'N' || 'O' || 'F' || 'P' || 'S' || 'I' || 'U'){
      output.push(char[i]);
   }else{
      output.push('0');
   }
}
console.log(output);

I had it with cases first and it worked but looked way too much so I thought I try or but I get an output of the input

what I expect is this:

["H", "I", "S", "F", "0", "N", "0", "O", "0"]

Answer 1

The pattern

char[i] == 'H' || 'K' || 'Y'

returns the first truthy value, which is the comparison with 'H' or if the comparison is false, it takes 'K'. All other strings are not used.

For taking a check if the character is in an array or a string, you could use includes (Array#includes/String#includes) which checks a given value against an array or string and returns true or false.

This proposal uses Array.from which takes a string, (basically any iterables, or an object with a length property) and returns an array of characters. An while this method contains a mapping functionality, you could check the character and return a differetn character, based on the check.

var input = 'HISFANTOR',
    output = Array.from(input, c => 'HKYVBCNOFPSIU'.includes(c) ? c : 0);

console.log(...output);