Why initialization of a variable returns undefined in console?

Question

whenever we define a variable in console with some value for example

var f = 20;
var j = 30;

the above statement returns undefined for one time, can you please help in understanding why it returns undefined even it we have defined both the variables? Secondly if it is related to hoisting then why undefined is coming only once?

The undefined is just the "output" of the console input. I think its only shown once for a better overview like 1 input == 1 output. — Teemoh, May 14 '17 at 17:31

score -1 · Answer 1 · answered May 14 '17 at 17:30

-1

The console reports the result of evaluating the expression, equivalent to typeof basically.

typeof eval("var f = 20;");

returns undefined

answered May 14 '17 at 17:30

bamtheboozle

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the comparison you had here at first I think addressed his confusion, you should consider putting it back and dinstinguishing the results – roberto tomás May 14 '17 at 17:32
Then why following statement typeof eval("(function(){return true;})()") not returning boolean – Sanchit Goel May 14 '17 at 17:36
It does return boolean for me in chrome dev console. I think it depends on the browser you're using. – bamtheboozle May 14 '17 at 17:37
@DragoşPaulMarinescu This is completely wrong. The console evaluates `a=3` and outputs 3, but the typeof would be number. – Andrew Li May 14 '17 at 17:39

Why initialization of a variable returns undefined in console?

1 Answers1