javascriptnode.jsv8executioncontext

Why is variable undefined in global object even though it has not been defined?

I have this code:

console.log(apple);

If I run the program, I get the following result:

console.log(apple);
            ^

ReferenceError: apple is not defined

This is what I expected, but if I modify the code to print the apple variable from the global object, I get undefined

console.log(global.apple);

Result:

undefined

How is this undefined? As per my understanding, this should give the ReferenceError too right? Sorry if this is a simple concept, I am trying to understand the fundamentals. Any reference would be helpful.

Solution

  • What you're forbidden to do is reference a standalone identifier that the interpreter cannot resolve.

    Referencing a property of an object - even if the property doesn't exist - is perfectly fine. It will result in undefined, but it won't throw.

    const obj = {};
console.log(obj.foo);