By using the call and apply prototype methods of Functions. For example: function example () { console.log(this); } example.call(window); this will be the window variable. example.call(‘a string’); this will be a string. Call and apply are similar to each other, they both call the function and change the scope (the “this” variable) of the function, but where they are different is that apply takes an array of parameters to push onto the function, while call takes extra arguments, for example function testing (var1, var2) { console.log(‘var1: %o var2: %o’, var1, var2); } testing.apply(window, [‘parameter 1’, ‘parameter 2’]); will log “var1: parameter 1 var2: parameter 2”, to do the same with call, would be similar to this: testing.call(window, ‘parameter 1’, ‘parameter 2’); Hope this helps. If you need any more help with this, feel free to just ask.