ReferenceError: "x" is not defined

ReferenceError: "x" is not defined

?

, -. , , ( scope).

: ( jQuery), , , "$". <script> .

foo.substring(1); // ReferenceError: foo is not defined

var foo = "bar";
foo.substring(1); // "ar"

. , , .

function numbers() {
  var num1 = 2,
    num2 = 3;
  return num1 + num2;
}

console.log(num1); // ReferenceError num1 is not defined.

, , , . , , , .

var num1 = 2,
  num2 = 3;

function numbers() {
  return num1 + num2;
}

console.log(num1); // 2

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This page was last modified on 27 . 2025 . by MDN contributors.