In JavaScript, we can get a Random number; however, this number is between 0 and 1 which is not very useful when we want to work with integers.
For example, executing the random method of the Math Object we can get something like this:
Math.random(); // 0.7427427755721524 Math.random(); // 0.001514993949523702 Math.random(); // 0.4938488937880676
Many languages like PHP have a random function that takes two integers as parameters and returns a number in the range of the value of the two integers. (The range include the parameters). For example, we can do this in PHP:
rand(10,20); //12 rand(10,20); //18 rand(10,20); //17
We can emulate this with the following function:
function randomFromTo(from, to){
return Math.floor(Math.random() * (to - from + 1) + from);
}
randomFromTo(10,20); //18
randomFromTo(10,20); //10
randomFromTo(10,20); //15
randomFromTo(10,20); //20
What about using it as part of the JavaScript Core?
Most of developers do not recommend extending the built-in objects because it can create confusion among developers working on the same project. However, there are a lot of frameworks that extend the built-in object like Prototype. The way to do it is by using the prototype object that is part of all objects created in JavaScript. Example:
if(!Math.randomFromTo){
Math.randomFromTo = function(from, to){
return Math.floor(Math.random() * (to - from + 1) + from);
};
}
With this piece of code we can call the method from the Math Object like this:
Math.randomFromTo(100,1000) //950
How to get a random item from an array
If you want to go beyond, you can add a new method to the Array Object which would return a random element. Example:
if (!Array.prototype.random) {
Array.prototype.random = function() {
return this[Math.randomFromTo(0, this.length - 1)];
}
}
Now we can use the randomItem method like this:
[13, 5, 86, 11, 15].random(); //11
This would return one of the items of the array randomly.