Additive assignment operator (=). Adds the variable value to the expression value and assigns the sum to the variable.
It is often used when writing JavaScript. To be honest, I didn’t understand it very well before. After reading a lot of code, I feel that it is just because a variable is too long that it needs to be written in several lines. But it solved my other problems.
Sometimes we need to use a series of HTML codes as variables, and HTML sometimes contains some quotation marks. For example,