未捕获的ReferenceError：未定义xyz

Question

why do I get a not defined error when defining this function with single quotes?

example:

rotator.doStuff =  function(num) {
        //do stuff
        rotator.timer = setTimeout('rotator.doStuff('+num+')',500);
}

Answer 1

Assuming that this is the contents of an IIF.

When using a string, rotator will be resolved in the global scope, and it won't be available there, thus the error.

You should try this. Now rotator will resolved in lexical scope, from which it is accessible.

rotator.timer = setTimeout(rotator.doStuff.bind(rotator, num), 500);