How Can You Handle Optional Function Parameters in JavaScript Beyond Conditional Assignment?

Optional Function Parameters in JavaScript: Enhancements Beyond Conditional Assignment

JavaScript offers a common approach to handling optional function parameters using conditional assignment:

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

While this method is straightforward, it has limitations. It can fail if the optional argument is passed but evaluates to false. A more robust solution involves using the typeof operator:

if (typeof optionalArg === 'undefined') { optionalArg = 'default'; }

Alternatively, an idiom that provides greater flexibility is:

optionalArg = (typeof optionalArg === 'undefined') ? 'default' : optionalArg;

This syntax not only handles undefined optional arguments but also provides an elegant way to set defaults for parameters with falsy values.

These approaches offer a more reliable and consistent way to handle optional function parameters in JavaScript, ensuring that you have a default value even when the argument is passed as false or null.

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