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javascriptswitch-statementcontains

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


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");
}

Solution

  • "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.