JavaScript ReferenceError - Reference to undefined property "x"
Last Updated :
23 Jul, 2024
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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.
<!DOCTYPE html>
<html>
<head>
<script src=
"https://code.jquery.com/jquery-3.5.0.js">
</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.
<!DOCTYPE html>
<html>
<head>
<script src=
"https://code.jquery.com/jquery-3.5.0.js">
</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:
