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JavaScript JavaScript Basics (Retired) Storing and Tracking Information with Variables Combining Strings

Why doesn't using the 'message +=' more than once, for eg. three times, repeat that message three times as well?

I'm on the javascript basics course and learned that I can add strings together with a variable name by adding +=. However, in the tutorial, it's showing me to that I can use this more than once, like for example, message +=. After writing it, I expected for the message to be repeated the same amount of times as I wrote it, but this wasn't the case. Why?

2 Answers

I'm not entirely sure what your asking, but I'll explain how the += works and that should cover it

Okay so lets say we have a message,

var message = "Hello, ";

we now want to add our name to the message, there are two main ways we could do this.

message = message + "Emily"


message += "Emily"

Both statements have the same outcome, but the second one is shorter.

When we use the += operator, we are telling javascript to get the old variable value (in the left), and add the value to the right.

If we were to do this mulitple times, it may look something like this:

var msg = "";
msg += "Hello, "; //msg == "Hello, "
msg += "Emily"; //msg == "Hello, Emily"
msg += "! How are you?"; //msg == "Hello, Emily! How are you?"
msg += msg; //msg == "Hello, Emily! How are you?Hello, Emily! How are you?"
jason chan
jason chan
31,009 Points

plus equal is for concatenation or increment.