Where Will We Go

"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.