OR statement being ignored

Question

I'm trying to fire my masterFunction only if certain keys are pressed. However it's being called regardless of what button is clicked. Even though the console log shows a different key.

Can anyone advise?

//Update display on keydown event
addEventListener('keydown', (e) => {
    pressedKey = event.key;
    console.log(pressedKey);
    keyDownOperatorMapping(e);
});

let keyDownOperatorMapping = (e) => {
if (pressedKey === "+" || "-" || "*" || "Enter" || "Backspace" || "." || "/") {
masterFunction(e);
} 
};

Example: https://jsfiddle.net/rykawgs9/

Does this answer your question? [What's the prettiest way to compare one value against multiple values?](https://stackoverflow.com/questions/9121395/whats-the-prettiest-way-to-compare-one-value-against-multiple-values) — pilchard, Jun 04 '22 at 12:47
which itself is a duplicate linking to [Check variable equality against a list of values](https://stackoverflow.com/questions/4728144/check-variable-equality-against-a-list-of-values) — pilchard, Jun 04 '22 at 12:48
Thinking about the priority of the operators in your test: if (pressedKey === "+" || "-" || "*" || "Enter" || "Backspace" || "." || "/") is equivalent to if ((pressedKey === "+") || "-") as the first test gives false (if the key is no +) so the system moves onto the next value which is non zero (it is "-") so not false. The next ORs are not evaluated. The condition is always true. — A Haworth, Jun 04 '22 at 13:15

score 2 · Answer 1 · answered Jun 04 '22 at 12:57

It is because your current condition is

Hey is pressedKey equal is "+" or is "-" is true or //goes on

As string with length more than one is always one it always return true your condition is always true

So one way archive these

addEventListener('keydown', (e) => {
  pressedKey = event.key;
  console.log(pressedKey);
  keyDownOperatorMapping(e);
});

let keyDownOperatorMapping = (e) => {
  const keys = ["+", "-", "*", "Enter", "Backspace", ".", "/"]
  if (keys.includes(pressedKey)) {
    console.log("Found");
  }
};

score 1 · Accepted Answer · edited Jun 04 '22 at 13:14

1

You have to put the variable that you are comparing to. Which is in your case, the pressedKey:

if (pressedKey === "+" || pressedKey === "-" || pressedKey === "*" || pressedKey === "Enter" || pressedKey === "Backspace" || pressedKey === "." || pressedKey === "/")
...

edited Jun 04 '22 at 13:14

Zach Jensz

3,650
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answered Jun 04 '22 at 12:46

markcalendario

218
2
9

Ah thanks I've made this one before...! Cheers. – Sam Jefferies Jun 04 '22 at 12:47
This is correct, but it's a 12 year old duplicate – pilchard Jun 04 '22 at 12:49

score 1 · Answer 3 · answered Jun 04 '22 at 13:05

1

You can reduce the code a little by adding the searchable keys to an array, and then check that the array includes the key that was entered.

const allowed = ['+', '-', '*', 'Enter', 'Backspace', ',', '/'];

document.addEventListener('keydown', (e) => {

  const { key } = e;

  if (allowed.includes(key)) {

    // masterFunction(e)
    console.log(key);

  }

});

Additional documentation

Destructuring assignment

answered Jun 04 '22 at 13:05

Andy

61,948
13
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12 year old duplicate. – pilchard Jun 04 '22 at 13:07
While I agree with you, that dupe needs _a lot_ of curating. There are answers there spanning an entire 12 years, and is confusing, and JS has moved on. Sometimes it's easier to create a new answer that belongs in this decade. @pilchard – Andy Jun 04 '22 at 13:19
Hmmm, [answer with second most votes](https://stackoverflow.com/a/40910577/13762301) `if ([].includes()) { …` pretty confusing. – pilchard Jun 04 '22 at 14:34

OR statement being ignored

3 Answers3