JavaScript Logical AND assignment (&&=) Operator

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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.

Javascript

<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.

HTML

<h1 style="color:green"> 
    Geeksforzambiatek 
</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>