With JavaScript, what is the correct code to return a random number between 0 and 1? code example

Example 1: javascript random number between 0 and 10

Math.floor(Math.random() * 10);

Example 2: javascript random number 1 or -1

//an equation that returns either 1 or -1
var number = ((Math.floor(Math.random() * 2) - 2) * 2) + 1