javaScript for/loop scope

Question

I have written this bit of code that sums the values of array. Can some one please explain why I'm getting undefined in the last console.log statement.

var array = [2,3,4,5,6,7];
var sum = 0;

for(var i = 0; i < array.length; i++) { 
    sum = array[i] + sum; 
}

console.log(sum);
console.log(array[i]);

Hint: if i < array.length returns true, you'd still be in your for loop. — nhgrif
– nhgrif, Commented Nov 24, 2013 at 2:57

Benjamin Gruenbaum · Accepted Answer · 2013-11-24 02:53:50Z

5

That's because the loop performed i++ and now i is equal to array.length.

JavaScript returns the primitive value undefined when you're trying to access object properties that were not previously defined.

The array however is only filled between places 0 and array.length - 1 since JavaScript arrays are 0 based.

answered Nov 24, 2013 at 2:53

Benjamin Gruenbaum

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