What is the meaning of adding a + in js?

Question

I have a condition in reactjs that starts with

+this.state.isCompleted

Why do we write + ?

Answer 1

Is a forced conversion to number

const str = '1'
const bool = false
const fail = 'isNan?'

const num = +str
const numBool = +bool
const numFail = +fail

console.log(typeof num, typeof numBool, numFail)