If you desperately want to do this, you can try using eval():

var data = "testVariable"; eval("var temp_" + data + "=123;"); alert(temp_testVariable);

Or use window object:

var data = "testVariable"; window["temp_" + data] = 123; alert(window["temp_" + data]);

tl;dr:Don't useeval!

There is no single solution to this. It is possible to dynamically accesssomeglobal variables through thewindow, but this does not apply to local variables of a function.Global variables that do notbecomewindowattributes are variables defined withletandconst, andclasses.

There is almost always a better solution than using mutable variables!Instead, you should look atdata structuresand choose the correct data structure for your problem.

If you have a fixed set of names like

// BAD - DON'T DO THIS!!! var foo = 42; var bar = 21; var key = 'foo'; console.log(eval(key));