CODEWITHSUNDEEP
javascripttry-catch
B--rian
B--rian

Reputation: 5890

Why would one implement the same function both in the try- and the catch-phrase?

I'm trying to understand a rounding function I found in inherited JavaScript code:

function percentageWithCommas(x?) {
    try {
        return (x * 100).toLocaleString("en-UK", { 
          maximumFractionDigits: 1, minimumFractionDigits: 1 }) + '%';
    } catch (e) {
        return (x * 100).toFixed(2) + '%';
    }
}

I understand that rounding in JS is nowadays done with .toLocaleString(...) rather than .toFixed().

Why would one implement the same thing in both the try and the catch phrase?

Reference

Upvotes: 0

Views: 51

Answers (1)

Tralgar
Tralgar

Reputation: 300

A double implementation seems to be useless: toLocaleString() has a high compatibility with old browsers, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toLocaleString

Different issue: You should not use (x?) because if x is optional, you will have a problem with a null * 100. You better test if x is a number and do:

function percentageWithCommas(x) {
    if(isNaN(x)) return '';
    return (x * 100).toLocaleString("en-UK", { 
      maximumFractionDigits: 1, minimumFractionDigits: 1 }) + '%';
}

or something like that.

Note: In case you are worried that .toLocalString is not available, you can explicitly check for its existence with if ((0).toLocaleString).

Upvotes: 1

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