javascript not equal to

JavaScript is a programming language widely used in Internet applications. It allows developers to add dynamics and interactivity to web pages. There are various comparison operators in JavaScript, including the "equal" operator and the "not equal" operator. In this article, we will explore the role of the "not equal to" operator in JavaScript and its usage.

The "not equal to" operator in JavaScript indicates inequality. When writing JavaScript code, we use the inequality operator to compare two values ​​to see if they are not equal. In JavaScript, the "not equal" symbol consists of an exclamation point and an equal sign (!==).

At this point you may be thinking, what is the corresponding "equal" symbol? In JavaScript, the "equals" symbol represents equality, which consists of two equal signs (==). What needs to be remembered is that in order to avoid the disadvantages of type conversion, "===" or "!==" should be used when comparing two values.

Here are some examples of the "not equal to" operator. Suppose we have two variables a and b:

• If a is not equal to b, return true: a!==b.
• If a equals b, return false: a!==b.
• Except for the type, the values ​​​​of a and b are exactly the same, return false: a!==b.

From these examples, you can see that the Not Equal operator is used to compare two values ​​to see if they are not equal. This operator returns true when a and b have different values ​​or types. Otherwise, the operator returns false.

The issue of type conversion was mentioned before. Due to the dynamic type characteristics of JavaScript, it may show different types in different contexts, which may have an impact on comparison operations. However, the Not Equal operator has stronger type checking capabilities and therefore avoids the effects of type conversions when comparing two values. This type of comparison is called "loose comparison".

In addition, the "not equal to" operator has a similar usage, that is, "not equal to equal to" (!=). Sometimes you may need to compare two values ​​directly without considering their types or checking whether they are similar. In this case, you can use the "not equal to equal" operator.

There are some common situations where you can use the "not equal to" operator:

1. Checking whether a variable is different from a certain value

Suppose we There is a variable num and we want to check if it is not equal to 0. We can use the following code:

if(num !==0){

console.log("num 不等于 0");

}else{

console.log("num 等于 0");

}

2. Don’t wait Value Comparison

Suppose we have a variable x, which may contain text strings or numbers. We want to check if it is not equal to the specified value. We can use the same operator ("not equal to" or "not equal to equal") to compare regardless of the type of the value stored in the variable x:

if (x != " hello") {

console.log("变量x不等于'hello'");

}

3. Processing logical operations

The "not equal to" operator is most frequently used in conditional statements. For example if statement. In the if statement, a Boolean expression is defined whose result is true or false. If the expression is false, the if statement block is skipped. For example:

if(num !== 0 && num < 10){

console.log("num 不等于 0 且小于 10");

}else{

console.log("num 等于 0 或不小于 10");

}

In this example , if num is not equal to 0 and less than 10, the first code block will be executed. Otherwise, the else statement block will be executed.

In this article, we discussed the “not equal to” operator in JavaScript. Although it is very convenient to use this operator to compare two values ​​of different types, it should be noted that in order to avoid type conversion errors, we should use "!==" instead of "!=" when comparing two values. . At the same time, be careful to use correct Boolean expressions when using conditional statements to avoid logical errors.

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