Is it possible to use .contains() in a switch statement?

Question

This is just a simple example of what I'm trying to do:

switch (window.location.href.contains('')) {
    case "google":
        searchWithGoogle();
        break;
    case "yahoo":
        searchWithYahoo();
        break;
    default:
        console.log("no search engine found");
}

If it's not possible/feasible what would be a better alternative?

Solution:

After reading some of the responses I found the following to be a simple solution.

function winLocation(term) {
    return window.location.href.contains(term);
}
switch (true) {
    case winLocation("google"):
        searchWithGoogle();
        break;
    case winLocation("yahoo"):
        searchWithYahoo();
        break;
    default:
        console.log("no search engine found");
}

No. It would have to be `switch(true) { case location.href.contains("google") ...` which is plain silly — mplungjan, Jul 19 '14 at 18:02
Yes, but it won't do what you expect. The expression used for the switch is evaluated *once* - in this case that would be true/false as the result, not a string. — user2864740, Jul 19 '14 at 18:03
You need to use contains ('Google') and no if won't work in switch. Use if else — Esben Skov Pedersen, Jul 19 '14 at 18:03

user2864740 · Accepted Answer · 2014-07-19T18:14:35.367

35

"Yes", but it won't do what you expect.

The expression used for the switch is evaluated once - in this case contains evaluates to true/false as the result (e.g. switch(true) or switch(false)) , not a string that can be matched in a case.

As such, the above approach won't work. Unless this pattern is much larger/extensible, just use simple if/else-if statements.

var loc = ..
if (loc.contains("google")) {
  ..
} else if (loc.contains("yahoo")) {
  ..
} else {
  ..
}

However, consider if there was a classify function that returned "google" or "yahoo", etc, perhaps using conditionals as above. Then it could be used as so, but is likely overkill in this case.

switch (classify(loc)) {
   case "google": ..
   case "yahoo": ..
   ..
}

While the above discusses such in JavaScript, Ruby and Scala (and likely others) provide mechanisms to handle some more "advanced switch" usage.

edited Jul 19 '14 at 18:14

answered Jul 19 '14 at 18:04

user2864740

60,010
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220

1

Thank you for your answer. It helped me find a solution, which I updated the main answer to contain. – RayB Jul 19 '14 at 18:27
@Rayz321 Yes, that is a possible form too - it is not my preference/recommendation though. – user2864740 Jul 19 '14 at 18:46
3

Contains is not a method in javascript its include i.e. loc.includes("yahoo") – Rahul Tagore Nov 26 '19 at 10:31

score 19 · Answer 2 · answered Dec 18 '19 at 16:39

19

An alternative implementation might be this. Not much in it but reads better than switch(true)...

const href = window.location.href;
const findTerm = (term) => {
  if (href.includes(term)){
    return href;
  }
};

switch (href) {
  case findTerm('google'):
      searchWithGoogle();
      break;
  case findTerm('yahoo'):
      searchWithYahoo();
      break;
  default:
      console.log('No search engine found');
};

answered Dec 18 '19 at 16:39

TimT

1,576
16
14

At least it is in the answers section =) – ilkerkaran Dec 18 '19 at 16:43

Is it possible to use .contains() in a switch statement?

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