Answers for "check variable is valid in js"

How can I test whether a variable has a value in JavaScript?

if (typeof variable == "undefined") {...} --> return true if variable undefined

//An empty string evaluates to FALSE in JavaScript so you can just do:
if (variable) {...}

js check if variable is string

if (typeof myVar === 'integer'){
    //I am indeed an integer
}

if (typeof myVar === 'boolean'){
    //I am indeed a boolean
}