Javascript function returns true when it should return false - Stack Overflow

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I have a function that checks if a param exists in an array of inputs. It should return false but does not.

{
  ...
  validation: params => {
    const valid = ["valid", "inputs"];
    valid.forEach( v=> {
      if (!params.hasOwnProperty(v)) {
        return false;
      }
    });

    return true;
  }

So even when the if statement does evaluate to be true it never return false. This function always returns true no matter what.

I have a function that checks if a param exists in an array of inputs. It should return false but does not.

{
  ...
  validation: params => {
    const valid = ["valid", "inputs"];
    valid.forEach( v=> {
      if (!params.hasOwnProperty(v)) {
        return false;
      }
    });

    return true;
  }

So even when the if statement does evaluate to be true it never return false. This function always returns true no matter what.

• javascript

Share Improve this question Follow asked Sep 27, 2018 at 2:59 Joshua BlevinsJoshua Blevins 69711 gold badge1111 silver badges2828 bronze badges 3

• Because the return false stmt is of you callback's return stmt.try setting a boolean in callback and return on basic of that or use for loop instead. – Aagam Jain Commented Sep 27, 2018 at 3:06
• 1 Possible duplicate of Short circuit Array.forEach like calling break – NullPointer Commented Sep 27, 2018 at 3:06
• If someone can post how I could refactor this code to work the way I intend I can accept that as the answer. – Joshua Blevins Commented Sep 27, 2018 at 3:07

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2 Answers 2

Sorted by: Reset to default 7

As an alternative, use the right tool for the job. If you want to check whether every member of an array has a certain property, use every:

validation: params => {
  const valid = ["valid", "inputs"];
  return valid.every(v => params.hasOwnProperty(v));
}

You're return is returning from the callback function of forEach not the main function. You can't return early from a forEach without something like a throw. If you want to return early use a for...of loop instead:

validation: params => {
    const valid = ["valid", "inputs"];
    for (v of valid) {
      if (!params.hasOwnProperty(v)) {
      return false;  // this returns from the main function
    }
  };

  return true;
}

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