What does ?. mean in js?

The ?. (optional chaining operator) in JavaScript provides safe access to nested properties and prevents errors: if the property exists, its value is returned; if it does not exist, undefined is returned. Can be used to handle nested data structures that may be null or undefined. Advantages: Prevent errors, improve readability, and facilitate combination with other operators. Limitations: Inaccessible array elements, not assignable, may be less efficient than conditional statements or try...catch blocks.

?. (optional chaining operator) in JavaScript

?. Operator

?. (optional chaining operator) is a JavaScript operator used to safely access nested properties and prevent errors. If the object property or method exists, it returns that value; otherwise, it returns undefined.

Syntax

<code>object?.property</code>

Usage

The optional chaining operator is usually used to handle possible null or undefined nested data structure. For example:

<code class="javascript">const user = {
  name: "John",
  address: {
    street: "Main Street"
  }
};

console.log(user.address?.street); // "Main Street"</code>

In the above example, the address attribute may or may not exist. If it exists, we access the street property and print its value. If address does not exist, the optional chaining operator will return undefined, avoiding reference errors.

Advantages

Using the ?. operator has the following advantages:

• Prevents errors: It prevents quoting Error because if the property does not exist, it returns undefined.
• Improve code readability: It eliminates conditional statements and try...catch blocks, making the code easier to read.
• Easy to use in combination with other operators: It can be used in combination with other operators (such as ternary operators and logical operators) to create more complex conditional statements.

Limitations

It is worth noting that the ?. operator still has some limitations:

• It cannot be used for accessing array elements.
• It cannot be used for assignment.
• In some cases it may be less efficient than conditional statements or try...catch blocks.

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