For-loop and variables

Question

var prompt1 = prompt("Number Here");
var something2 = prompt("Increment Here");
for (var i = 5; i <= prompt1; i += 5) {
    alert(i);
}

http://jsfiddle.net/davidhin/wte7d5k9/

Why is it that when I change i += 5 to i += something2, the code stops working?

What does your fiddle have to do with your question? You'll need to clarify what you're asking by including more explanation of what you're doing and what you're trying to accomplish in your post. — kinakuta
– kinakuta, Commented Sep 30, 2014 at 8:00

magmel · Accepted Answer · 2014-09-30 07:58:44Z

6

Because something2 is String. Use in for loop Number(something2) to convert to Number.

answered Sep 30, 2014 at 7:58

magmel

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Comments

Kai · Accepted Answer · 2014-09-30 17:04:43Z

1

the prompt is receive a String value,not int value. Imagine that if someone put it prompt "hello" and "world", what will happen?

so you should do those steps :

1/. parse value into int data type.

2/. Validate data types.

example :

      var promptVal = parseInt(prompt1); // return NaN (not-a-number) if input isn't number.
      if(isNaN(prompVal)) {
         return error;
      }

Now you could run for-loop normally.

edited Sep 30, 2014 at 17:04

answered Sep 30, 2014 at 8:20

Kai

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