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JavaScript JavaScript Loops, Arrays and Objects Simplify Repetitive Tasks with Loops A Closer Look at Loop Conditions

Aaron Selonke
Aaron Selonke
10,323 Points
Posted by Aaron Selonke
Aaron Selonke
10,323 Points

This variable comes back as undefined, Alert message is 'undefined' not an error???

var Num; function OriginalRandomNumber() { Num = Math.floor( Math.random() * 10000 ) + 1; }

alert(Num);

This is not a universal scope variable, right? Why does the alert message come back as undefined?

2 Answers

Erwin Meesters
Erwin Meesters
15,088 Points
Erwin Meesters
Erwin Meesters
15,088 Points

First you declare a variable called Num, without a value. So it's undefined at this stage. Then you declare a function called OriginalRandomNumber which takes the variable Num and sets it's value to a random number. Without calling the function nothing will happen and the variable Num will stay undefined. So you have to call the function. 

var Num; 
function OriginalRandomNumber() { 
  Num = Math.floor( Math.random() * 10000 ) + 1; 
}
OriginalRandomNumber();
alert(Num);
Aaron Selonke
Aaron Selonke
10,323 Points
Aaron Selonke
Aaron Selonke
10,323 Points

Cheers! Calling the function helps.

The variable was declared outside of the function to keep it's scope universal.