How to check if a string contains a number in JavaScript?

Question

I don\'t get how hard it is to discern a string containing a number from other strings in JavaScript.

Number(\'\') evaluates to 0, while

Answer 1

Let's try

""+(+n)===n

which enforces a very rigid canonical way of the number.

However, such number strings can be created by var n=''+some_number by JS reliable.

So this solution would reject '.01', and reject all simple numbers that JS would stringify with exponent, also reject all exponential representations that JS would display with mantissa only. But as long we stay in integer and low float number ranges, it should work with otherwise supplied numbers to.