The inequality (!=) operator checks whether its two operands are not
equal, returning a Boolean result.
Unlike the strict inequality operator,
it attempts to convert and compare operands that are of different types.
Syntax
x != y
Description
The inequality operator checks whether its operands are not equal. It is the negation of the equality operator so the following two lines will always give the same result:
x != y;
!(x == y);
For details of the comparison algorithm, see the page for the equality operator.
Like the equality operator, the inequality operator will attempt to convert and compare operands of different types:
3 != "3"; // false
To prevent this, and require that different types are considered to be different, use the strict inequality operator instead:
3 !== "3"; // true
Examples
Comparison with no type conversion
1 != 2; // true
"hello" != "hola"; // true
1 != 1; // false
"hello" != "hello"; // false
Comparison with type conversion
"1" != 1; // false
1 != "1"; // false
0 != false; // false
0 != null; // true
0 != undefined; // true
0 != !!null; // false, look at Logical NOT operator
0 != !!undefined; // false, look at Logical NOT operator
null != undefined; // false
const number1 = new Number(3);
const number2 = new Number(3);
number1 != 3; // false
number1 != number2; // true
Comparison of objects
const object1 = {
key: "value",
};
const object2 = {
key: "value",
};
console.log(object1 != object2); // true
console.log(object1 != object1); // false