Javascript: While the variable is declared in global scope, it remains undefined inside the function

Question

While I define the starttime variable without the var keyword thus making it global, logging the starttime in console gives undefined .

 starttime = new Date();

setInterval(function(starttime){
    getTimeElapsed(starttime);
}, 1000);

How can I access the starttime variable inside the function?

Answer 1

You could try the following:

starttime = new Date();

setInterval(function(){
    getTimeElapsed(starttime);
}, 1000);

Now you access the global declared variable starttime . While in your code, you were accessing an undefined variable. Why? You function had one argument that you never passed to it. So it's value was undefined.

Answer 2

You have two variables called starttime .

One global, implicitly declared here:

 starttime = new Date(); 

and one local, declared here:

 function(starttime){ 

Since you don't use the local version, the best approach is to remove that declaration .

setInterval(function(){

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Alternatively, access the global explicitly:

getTimeElapsed(window.starttime);