javascript function toCelsius(fahrenheit) return (5/9) * (fahrenheit-32);} … Accept Solution Reject Solution. Define global variable in a JavaScript function. How to access the correct this inside a callback javascript I'd be surprised if I ran y() and x changed in the GlobalEnv.. Agree completely with @mara - I've always viewed environment changes as something that falls into the "just because … How to access a variable outside a subfunction in javascript Nested Functions in JavaScript We had to do that in our code for some reason...it's been a few months so forgot why. So, We can not redeclare it. Eg $.ajax({ url: 'includes/ajax_chart.php', data:{present:'present'}, … If you forget to code the var keyword in a variable declaration, the JavaScript engine assumes that the variable is global. A JavaScript global variable is declared outside the function or declared with window object. And to create a new scope, you need to create a function. Because prop-3 and 3 are invalid identifiers, the dot property accessor doesn't work:. Global and Local variables in JavaScript