JavaScript Logical OR assignment (||=) Operator
This operator is represented by x ||= y and it is called a logical OR assignment operator. If the value of x is falsy then the value of y will be assigned to x.
When we divide it into two parts it becomes x || ( x = y ).
It checks if x is true or false, if the value of x is falsy then it runs the ( x = y ) block and the value of y gets stored into x and if the value of x is truthy then the value of the next block ( x = y ) does not execute.
Syntax :
x ||= y
is equivalent to
x || (x = y)
Example 1: This example shows the use of the JavaScript Logical OR assignment (||=) Operator.
Javascript
<script> let name = { firstName: "Ram" , lastName: "" , }; console.log(name.firstName); // Changing the value using logical // OR assignment operator name.firstName ||= "Shyam" ; // But value does not change because // name.firstName is truthy console.log(name.firstName); console.log(name.lastName); // Changing the value using logical // OR assignment operator name.lastName ||= "Kumar" ; // The value changes because name.lastName is falsy console.log(name.lastName); </script> |
Output :
"Ram" "Ram" "" "Kumar"
Example 2: This example shows the use of the JavaScript Logical OR assignment (||=) Operator.
HTML
< h1 style = "color:green" >w3wiki</ h1 > < p id = "print_arr" ></ p > < script > let arr = [1, 2, "apple", null, undefined, []] // Replace each falsy values with "gfg" arr.forEach((item, index)=>{ arr[index] ||= "gfg" }) document.getElementById("print_arr").innerText = arr.toString(); </ 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
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