What does !== mean in js?

The !== operator in JavaScript is a strict inequality operator, used to compare whether two values ​​are equal. This operator takes into account type differences and is therefore more strict than the relaxed equality operator (==). Returns true if the two values ​​are of different types or have different values; otherwise, returns false.

The meaning of the !== operator in JavaScript

The !== operator in JavaScript is strictly not The equal operator is used to compare two values ​​to see if they are not equal.

Meaning:

!== operator compares two values. If the two value types are different or have different values, it returns true; otherwise, it returns false . Unlike the == operator (relaxed equality operator), it does no type conversion and is therefore more strict.

Syntax:

<code>variable1 !== variable2</code>

Usage scenarios:

!== operator is often used when strict comparison of equality is required Cases like:

• Make sure the values ​​of two variables are different
• Check if the value is null or undefined
• Compare variables of different types

Example:

<code>const num1 = 1;
const num2 = "1";

console.log(num1 !== num2); // true
// 即使值相同，但类型不同

const str1 = "Hello";
const str2 = "World";

console.log(str1 !== str2); // true
// 两个字符串值不同

const obj1 = {};
const obj2 = {};

console.log(obj1 !== obj2); // true
// 两个对象即使值相同，但引用不同

const nullValue = null;
const undefinedValue = undefined;

console.log(nullValue !== undefinedValue); // true
// 严格比较这两个特殊值</code>

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