JavaScript ReferenceError – Reference to undefined property “x”
Last Updated :
22 May, 2023
This JavaScript warning reference to undefined property occurs if a script tries to access an object property that doesn’t exist.
Message:
ReferenceError: reference to undefined property "x" (Firefox)
Error Type:
ReferenceError(Only reported by firefox browser)
Cause of the error: The script is trying to access an object property that doesn’t exist.
Example 1: In this example, the valid property is accessed, So the error has not occurred.
HTML
<!DOCTYPE html>
< html >
< head >
< script src =
</ script >
</ head >
< body style = "text-align: center;" >
< h1 style = "color: green;" >
GeeksforGeeks
</ h1 >
< p >
JavaScript ReferenceError
Reference to undefined property
</ p >
< button onclick = "Geeks();" >
click here
</ button >
< p id = "GFG_DOWN" ></ p >
< script >
let el_down = document.getElementById("GFG_DOWN");
function GFG() {
"use strict";
let AR_GFG = { prop_1: "Val_1" };
return AR_GFG.prop_1;
}
function Geeks() {
try {
GFG();
el_down.innerHTML =
"'Reference to undefined property'" +
" error has not occurred";
} catch (e) {
el_down.innerHTML =
"'Reference to undefined property'" +
"error has occurred";
}
}
</ script >
</ body >
</ html >
|
Output:
Example 2: In this example, the undefined property is accessed, So the error has occurred.
HTML
<!DOCTYPE html>
< html >
< head >
< script src =
</ script >
</ head >
< body style = "text-align: center;" >
< h1 style = "color: green;" >
GeeksforGeeks
</ h1 >
< p >
JavaScript ReferenceError
Reference to undefined property
</ p >
< button onclick = "Geeks();" >
click here
</ button >
< p id = "GFG_DOWN" ></ p >
< script >
let el_down = document.getElementById("GFG_DOWN");
function GFG() {
"use strict";
let GFG = {};
return GFG.prop1;
}
function Geeks() {
try {
GFG();
el_down.innerHTML =
"'Reference to undefined property'" +
"error has not occurred";
} catch (e) {
el_down.innerHTML =
"'Reference to undefined property'" +
"error has occurred";
}
}
</ script >
</ body >
</ html >
|
Output:
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