How to understand Incrementing variables in JS?

Asked Dec 10 '20 at 16:32

Active Dec 10 '20 at 16:32

Viewed 61 times

I am a junior developer learning JS. Here is the piece of code I am practicing today.

I see the line " (var x=0; x < str1.length; x++) " almost every example I work on.

Can someone please explain what the mechanics are doing? Why do we always set a var equal to 0? What role does str1.length play in this line?

function vowel_count(str1) {
  var vowel_list = 'aeiouAEIOU';
  var vcount = 0;

  for (var x = 0; x < str1.length; x++){
    if (vowel_list.indexOf(str1[x]) !== -1)
    {
      vcount += 1;
    }

  }

  return vcount;

}

console.log(vowel_count("The quick black panther."));

asked Dec 10 '20 at 16:32

tony_ysl

2

It should be adequately explained on MDN https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Loops_and_iteration#for_statement. This goes through what all the terms are and the order of execution – phuzi Dec 10 '20 at 16:35
2

Just look at [the documentation](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Loops_and_iteration). – Scott Marcus Dec 10 '20 at 16:35
`str1.length` = length of `str1` and `var x=0` is for initialising x with 0, you should read about basic for loop – Abishek Kumar Dec 10 '20 at 16:36
@phuzi will check that out – tony_ysl Dec 10 '20 at 16:44
@ScottMarcus will do – tony_ysl Dec 10 '20 at 16:44
@AbishekKumar will do – tony_ysl Dec 10 '20 at 16:45
can you one of you please explain how the index of works in this line – tony_ysl Dec 11 '20 at 02:03
if (vowel_list.indexOf(str1[x]) !== -1) – tony_ysl Dec 11 '20 at 02:03
Check out the [documentation](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf) – phuzi Dec 11 '20 at 09:15

How to understand Incrementing variables in JS?

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