JS obtains random number function and can customize the minimum and maximum values ​​_javascript skills

/**
* lowerValue minimum value
* upperValue maximum value
*/
function selectFrom(lowerValue , upperValue){

//Total number of value ranges
var choices = upperValue - lowerValue 1;
return Math.floor(Math.random() * choices lowerValue);
}
var num = selectFrom(2, 10);
alert(num);//A value between 2 and 10 (inclusive)

var colors = ["red ","green","blue","yellow","black","brown"];
var color = colors[selectFrom(0, colors.length-1)];
alert(color) ;//May be any value contained in the array