JavaScript Logical AND assignment (&&=) Operator

This operator is represented by x &&= y, and it is called the logical AND assignment operator. It assigns the value of y into x only if x is a truthy value.

We use this operator x &&= y like this. Now break this expression into two parts, x && (x = y).  If the value of x is true, then the statement (x = y) executes, and the value of y gets stored into x but if the value of x is a falsy value then the statement (x = y) does not get executed.

Syntax :

x &&= y

is equivalent to 

x && (x = y)

Example: This example shows the basic use of the Javascript Logical AND assignment(&&=) operator.

<script>  let name = {  firstName: "Ram",  lastName: "",  };    console.log(name.firstName);    // Changing the value using logical  // AND assignment operator  name.firstName &&= "Shyam";    // Here the value changed because  // name.firstName is truthy  console.log(name.firstName);    console.log(name.lastName);    // Changing the value using logical   // AND assignment operator  name.lastName &&= "Kumar";    // Here the value remains unchanged   // because name.lastName is falsy  console.log(name.lastName); </script> 

Output :

"Ram" "Shyam" "" ""

Example 2: This example shows the basic use of the Javascript Logical AND assignment(&&=) operator.

<h1 style="color:green"> Geeksforgeeks </h1> <h3> Javascript Logical AND assignment(&&=) operator </h3> <p id="print_arr"></p> <script>  let arr = [1, 2, "apple", null, undefined, []]    // Replace each truthy values with "gfg"    arr.forEach((item, index)=>{  arr[index] &&= "gfg"  })    document.getElementById("print_arr").innerText = arr.toString();  //console.log(arr) </script> 

Output :

We have a complete list of Javascript Operators, to check those please go through the Javascript Operators Complete Reference article.

Supported Browsers:

• Chrome 85
• Edge 85
• Firefox 79
• Safari 14