What is the JavaScript Object Literal Property Value Shorthand `{a, b, c}`?

Object Literal Property Value Shorthand Explained: What is {a, b, c} in JavaScript?

Question:

In JavaScript, the syntax var f = {a, b, c}; introduces a data structure that appears to combine an object literal and an array. What exactly is this syntax, and how does it compare to traditional object literals?

Answer:

Introduced in ES6 (ECMAScript 2015), the syntax var f = {a, b, c}; is known as Object Literal Property Value Shorthands. It provides a shorthand notation for initializing an object literal, where the property names are derived from the variable names.

This syntax is functionally equivalent to:

var f = {a: a, b: b, c: c};

Essentially, it eliminates the need to explicitly specify the property keys, making for more concise and readable code. This shorthand can also be combined with traditional object initialization, as seen in:

var f = {a: 1, b, c};

This feature is particularly useful when creating objects that hold a set of data with matching property and variable names. For instance, to create an object from an array of values, one can use:

var arr = [1, 'x', true];
var obj = {a: arr[0], b: arr[1], c: arr[2]};

Using the property value shorthand, this can be written as:

var obj = {a, b, c};

This syntax provides a powerful tool for creating and initializing objects in JavaScript. Refer to the documentation on Property definitions in Object initializer for more information.

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