Why is there sometimes a semicolon before an anonymous function?

Question

I often encounter this:

;(function (window) {
    // ...
}(window);

I know that this anonymous function is called providing the window as the scope. But why is there a semicolon before it? I have never used that myself.

It's there doing exactly what semicolons do, separating expressions, making sure the anonymous function is not included to a previous expression. — Teemu, Nov 08 '13 at 16:47
Where have you seen it written like that? Looks like something to prevent errors from a bad copy paste job. — ericjbasti, Nov 08 '13 at 16:48

score -1 · Accepted Answer · answered Nov 08 '13 at 16:47

By putting it there, it ensures the preceding statement was closed. It's particularly important when you are minifying JavaScript code. One of the most common problems there is when you don't have one file that ends with neither a new line nor a semicolon and gets merged with one that starts with neither. That effectively merges the last statement of the first file with the first line of the second file resulting in syntax errors.

Why is there sometimes a semicolon before an anonymous function?

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