// native returns true if the variable does NOT contain a valid number
isNaN(num)
// can be wrapped for making simple and readable
function isNumeric(num){ return !isNaN(num)
}
isNumeric(123) // true
isNumeric('123') // true
isNumeric('1e10000') // true (This translates to Infinity, which is a number)
isNumeric('foo') // false
isNumeric('10px') // false

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

function isNumeric(num){ return !isNaN(num)
}
isNumeric("23.33"); //true, checking if string is a number. 

isNaN(num) // returns true if the variable does NOT contain a valid number
isNaN(123) // false
isNaN('123') // false
isNaN('1e10000') // false (This translates to Infinity, which is a number)
isNaN('foo') // true
isNaN('10px') // true

function isNumeric(str) {	// Check if input is string	if (typeof str != "string")	return false	// Use type coercion to parse the _entirety_ of the string // (`parseFloat` alone does not do this).	// Also ensure that the strings whitespaces fail	return !isNaN(str) &&	!isNaN(parseFloat(str))
}

isNaN(num) // returns true if the variable does NOT contain a valid number

function isNumeric(str) { if (typeof str != "string") return false // we only process strings! return !isNaN(str) && // use type coercion to parse the _entirety_ of the string (`parseFloat` alone does not do this)... !isNaN(parseFloat(str)) // ...and ensure strings of whitespace fail
}

typeof "ssss"