Generate an array with a random length, with distinct random values.

randomArray.js

/**
 * 
 * Usage: generateArray(10)
 * Where 10 is the maximum allowed length (and value range) of the array.
 * 
 * Example output: [5, 3, 9, 1, 0, 2]
 * 
 * 
*/ 

var generateArray = function(maxItems) {
	var items = Math.floor(Math.random() * maxItems) + 1; // Change to reference maxItems if you want a static length
	var arr = [];

	for(var i = 0; i < items; i++) {
		var isDifferent = false;
		var randomNumber;

    // This loop will try numbers until it generates one that doesn't already exist.
		while(!isDifferent) {
			if(arr.length === 0) isDifferent = true; // No need to do it more than once if the array is still empty

			randomNumber = Math.floor(Math.random() * (maxItems - 1)) + 0; // Remove '-1' and change '0' to 1 if you don't want the values to be zero-indexed.

			if(arr.indexOf(randomNumber) === -1) {
				isDifferent = true;
			}
		}

		arr.push(randomNumber);
	}

	return arr;
};