Testing for a number within an array

Question

The .length and values of the array however are randomly assigned. More specifically, a() randomly assigns anArray.length to a random value 1-3, and the values therein are also randomly assigned a value 1-3. I've coded numTester() to test for 2 within anArray after a() is executed.

var anArray = [];
var numTester = function(aryParam, v) {

  var i;
  for (i = 0; i < aryParam.length; i++) {

    if (aryParam[i] == v) {

      return true;

    }

    return false;

  }

};
var a = function() {

  b = 0;

  c = setInterval(function() {

    b++;
    d = Math.floor(Math.random() * 3) + 1;
    anArray.push(d);

    if (b == d || b == 3) {

      clearInterval(c);
      document.write(anArray.join(", "), "<br />", numTester(anArray, 2));

    }

  }, 1);

};
a();

numTester() is supposed to return true if 2 is any of 1, 2, or 3 numbers within the array. The issue is that I've found that it will only return true if the first number of the array is 2. Why is this?

var anArray = [];
var numTester = function(aryParam, v) {

    var i;
    for(i = 0; i < aryParam.length; i++) {

        if(aryParam[i] == v) {

            return true;

        }

        return false;

    }

};
var a = function() {

    b = 0;

    c = setInterval(function() {

        b++;
        d = Math.floor(Math.random() * 3) + 1;
        anArray.push(d);

        if(b == d || b == 3) {

            clearInterval(c);
            document.write(anArray.join(", ") + "<br />", numTester(anArray, 2));

        }

    }, 1);

};
a();

Looks like a use case for Array.prototype.some: anArray.some(x => x == v). ;-) — RobG
– RobG, Commented Jan 15, 2018 at 5:09

Heinrich · Accepted Answer · 2018-01-15 04:46:02Z

1

You return false in the for loop, your loop will only ever iterate once, need to move it outside the for loop.

var numTester = function(aryParam, v) {

    var i;
    for(i = 0; i < aryParam.length; i++) {
        if(aryParam[i] == v) {
            return true;
        }

        return false; <-- remove this
    }
    return false; <-- put it here
}

answered Jan 15, 2018 at 4:46

Heinrich

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1 Comment

Jay Over a year ago

jeez. now I feel dumb lol. That was actually quite obvious. Thanks a lot Heinrich.

JLRishe · Accepted Answer · 2018-01-15 04:47:26Z

1

Yes, have a good look at your for loop:

  for (i = 0; i < aryParam.length; i++) {

    if (aryParam[i] == v) {

      return true;

    }

    return false;

  }

The code in its body is:

if (aryParam[i] == v) {

  return true;

}

return false;

Which means it will either return true or false on its first iteration.

The solution:

Move the return false out of your loop:

  for (i = 0; i < aryParam.length; i++) {

    if (aryParam[i] == v) {

      return true;

    }


  }
  return false;

answered Jan 15, 2018 at 4:47

JLRishe

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Comments

Aswin Ramesh · Accepted Answer · 2018-01-16 05:44:18Z

0

you can use array.find

var numTester = function(aryParam, v) {
  return aryParam.find((ar) => ar == v) && true || false;
};

edited Jan 16, 2018 at 5:44

answered Jan 15, 2018 at 5:02

Aswin Ramesh

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