Meaning of the += operator when using a function?

If I see something like this:

myVariable += myF开发者_StackOverflowunction();

How does that work? Like, for example, is the myFunction() function supposed to return a value that is added to myVariable?

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That's correct. myFunction() is evaluated first, (e.g., it'll run and return its value), then its return value will be added to myVariable.

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Depends on your the result of your function and the value of your existing value that your are adding.

1. If the preceding myVariable is a string and the result is a number the values will be concatenated as a string.

2. If the preceding myVariable is a number and the result is a number the values will be handled as a sum of numbers.

3. If the preceding myVariable is a number or string but the result is a string the myVariable will be treated as a string, and the values will be concatenated.

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I assume it's the equivalent of

myVariable = myVariable + myFunction();