know what type one variable javascript code example

Example 1: javascript find type of variable

> typeof "foo"
"string"
> typeof true
"boolean"
> typeof 42
"number"

if(typeof bar === 'number') {
   //whatever
}

Example 2: javascript check type of variable var

> typeof "foo"
"string"
> typeof true
"boolean"
> typeof 42
"number"