We should understand `==` more, than not using it at all.

The behavior of the

operator (loose equal computing) in the

javascript is often confusing. Its secret is that it prefers numerical comparison. At first glance, this seems strange, but once you understand its working principle, you will understand the reasons behind this behavior and how to use it effectively. ==

Numerous priority

According to the ECMAScript specification,

The operational symbol follows the == abstract comparison algorithm . This algorithm has an obvious bias: it prefers to convert the value to numbers before comparison. The working principle is as follows:

If one value is

number
1. , and the other value is string , the string will convert to numbers. If a value is
Boolean value
2. , it converts it to numbers (true to 1, False convert to 0). If a value is
Object
3. (such as an array), use TOPRIMITIVE operation to convert it to its original value, and then repeat this process.
This means that when you use

, JavaScript usually performs more operations than you realize behind the scenes. It is not just a comparative value, but the first attempt to convert them into numbers.

== Important

Understanding this numerical priority can help you predict

behavior in different scenarios. For example:

== Here, the string "5" is converted into numbers 5, which is relatively successful. However, if you use , the type must be matched, so it returns false.

<code class="language-javascript">console.log(5 == "5"); // true</code>

This behavior is not random, it is to make some easier. For example, if you are comparing a number representing a string representation of the number,

can handle it without the need to explicit type conversion. ===

When to use

== Although is usually safer, in some cases,

is also useful. For example, if you are processing the data that may appear in the form of string or digital form (such as the user input from the form),

can simplify your code: ==

Here, Allows functions to process string and digital input without the need for additional type checking logic. === == A wider perspective ==

The key point is

<code class="language-javascript">function isAnswerCorrect(userInput, correctAnswer) {
  return userInput == correctAnswer;
}

console.log(isAnswerCorrect("42", 42)); // true</code>

itself is not bad, it is just a tool. The real problem appears when you use it in an unreasonable way, for example, compare the numbers with the array:

==

This is because the array is converted to a string ("42"), and then converted to numbers (42). However, just because it is effective does not mean a good idea. The problem here is not , but meaningless comparison.

== The operational symbols in JavaScript have numerical priority. Understanding this can help you write better and predictable code. Although is usually a safer choice, in specific scenarios, if the type of compulsory conversion is intentional and easy to understand, we should consider using === because it is also part of the language. ==

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