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Where Will We Go

February 6, 20212 min read

Lifestyle, JavaScript, Coding

"The real hidden features are the friends we made along the way." Jane Manchun Wong

Defaulting values

1.) Use ?? - nullish coalescing operator to default values if the variable is undefined or null.

Example where dataSet is an object.

const dataSet = {};

// destruct -> assign
const { expirationDate } = dataSet;

console.log(expirationDate ?? 'N/A');

For this example, the code above will return "N/A" because the expirationDate is not defined.

2.) Use the || - OR operator to default values if the variable is defined but falsy.

Here's an example with a key of an object to compare is defined but falsy.

const dataSet = {
  expirationDate: '', // <- defined
};

const { expirationDate } = dataSet;

console.log(expirationDate || 'N/A');

For this example, the code above will return "N/A" because the expirationDate is falsy. It is falsy because it is declared as an empty string.

Check the complete list of falsy values in JavaScript at MDN.

Summary

  • ?? - nullish coalescing returns the right side if the left value is either undefined or null.
  • || - OR operator returns the right side if the left value is falsy.
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