This JavaScript exception invalid assignment left-hand side occurs if there is a wrong assignment somewhere in code. A single “=” sign instead of “==” or “===” is an Invalid assignment.
Message:
ReferenceError: invalid assignment left-hand side
Error Type:
ReferenceError
Cause of the error: There may be a misunderstanding between the assignment operator and a comparison operator.
Basic Example of ReferenceError – Invalid assignment left-hand side, run the code and check the console
Example 1:
Javascript
if (Math.PI = 10 || Math.PI = 5) { console.log("Inside Loop");} |
Output:
ReferenceError: Invalid left-hand side in assignment
Example 1: In this example, “=” operator is misused as “==”, So the error occurred.
HTML
<!DOCTYPE html><html lang="en"><head> <title>Document</title></head><body style="text-align: center;"> <h1 style="color: green;"> neveropen </h1> <p> JavaScript ReferenceError - Invalid assignment left-hand side </p> <button onclick="Geeks();"> click here </button> <p id="GFG_DOWN"></p> <script> let el_down = document.getElementById("GFG_DOWN"); function Geeks() { try { if ((Math.PI = 10 || Math.PI = 5)) { document.write("Inside Loop"); } el_down.innerHTML = "'Invalid assignment left-hand side'" + " error has not occurred"; } catch (e) { el_down.innerHTML = "'Invalid assignment left-hand side'" + "error has occurred"; } } </script></body></html> |
Output:
Example 2: In this example, the + operator is used with the declaration, So the error has not occurred.
HTML
<!DOCTYPE html><html lang="en"><head> <title>Invalid assignment left-hand side</title></head><body style="text-align:center;"> <h1 style="color:green;"> neveropen </h1> <p> JavaScript ReferenceError - Invalid assignment left-hand side </p> <button onclick="Geeks();"> click here </button> <p id="GFG_DOWN"> </p> <script> let el_down = document.getElementById("GFG_DOWN"); function Geeks() { try { let str = 'Hello, ' + 'Geeks'; // Error Here el_down.innerHTML = "'Invalid assignment left-hand side'" + "error has not occurred"; } catch (e) { el_down.innerHTML = "'Invalid assignment left-hand side'" + "error has occurred"; } } </script></body></html> |
Output:
