How to Handle Optional Function Parameters in JavaScript?

Optional Function Parameters Enhanced in JavaScript

The conventional approach in JavaScript for handling optional parameters has been to assign a default value using the logical OR (||) operator:

function myFunc(requiredArg, optionalArg) {
  optionalArg = optionalArg || 'defaultValue';
}

However, this approach has limitations. For instance, if optionalArg is explicitly passed as an empty string or a number that evaluates to false, it will be overwritten by the default value.

A more robust solution is to employ an explicit empty check:

if (optionalArg === undefined) {
  optionalArg = 'defaultValue';
}

Alternatively, a concise idiom that achieves the same result is:

optionalArg = (optionalArg === undefined) ? 'defaultValue' : optionalArg;

These idioms clearly define the intention behind the code by explicitly checking for the undefined status of the optional parameter and assigning the default value only in that case. Choose the idiom that resonates best with your programming style and optimizes code comprehension.

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