Defining variable within if statement in javascript

Question

I want to assign a value to a variable when a condition is verified like this

if (k<12){

var Case=4;

}

The problem when i call this variable to be printed in the body of the page i get undefined

document.write(Case);

@NenadVracar its false statement .Because k is undefined .And case also defined inside the if is true .So you get undefined .declare the case as a global one.And don't forget define the k — prasanth
– prasanth, Commented May 13, 2017 at 10:00
@NenadVracar i have big code and the var declaration is in a function in the head and the call is in the body — S.ElBahloul
– S.ElBahloul, Commented May 13, 2017 at 10:00

Nina Scholz · Accepted Answer · 2017-05-13 09:59:52Z

3

Basically your var statement gets hoisted and assigned with undefined.

Variable declarations, wherever they occur, are processed before any code is executed. The scope of a variable declared with var is its current execution context, which is either the enclosing function or, for variables declared outside any function, global. If you re-declare a JavaScript variable, it will not lose its value.

Order of execution:

var Case;        // hoisted, value: undefined

if (k < 12) {
    Case = 4;
}

answered May 13, 2017 at 9:59

Nina Scholz

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Comments

user8003769 · Accepted Answer · 2017-05-13 10:03:25Z

1

You are getting undefined because you have not actually defined it. You are defining it when the condition is true. You should write the code like this.

var Case = null;
var k = 0;

if(k > 14) {
  Case = 3;
}

document.write(Case);

I hope it was helpful.

answered May 13, 2017 at 10:03

user8003769

Comments

Gustav P Svensson · Accepted Answer · 2017-05-13 10:02:10Z

0

var Case = 0;
if(k<12){
  Case = 4;
}
document.write(Case);

You need to define it first so if k<12 == False it wont be undefined.

answered May 13, 2017 at 10:02

Gustav P Svensson

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