What is the JavaScript += Operator and How Do You Use It?

In JavaScript, the += operator is used to add a value to a variable. For example:

let x = 5;
x += 3; // x is now equal to 8

The += operator can be used with other data types in JavaScript as well, such as strings. For example:

let str = "Hello";
str += " World"; // str is now equal to "Hello World"

In the above example, the += operator is used to concatenate the string "World" to the end of the string "Hello".

Overall, the += operator is a convenient shorthand for adding a value to a variable and reassigning the result to that variable. It is equivalent to writing x = x + y, where x is the variable and y is the value to be added.