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JavaScript: Getting random value from an array
var numbers = new Array('1','2','4','5','6','7','8','9','10');
I have a JavaScript Array and now want to randomly choose four different numbers from it and then express it on the page (through document.write). Obviously each time the page is reloaded by the user it would show four different random numbers.
You could shuffle the array and pick the first four.
numbers.sort( function() { return 0.5 - Math.random() } );
Now numbers[0], numbers[1]... and so on have random and unique elements.
Note that this method may not be an optimal way to shuffle an array: see Is it correct to use JavaScript Array.sort() method for shuffling? for discussion.
number.filter(() => Math.round(Math.random()) to get random items and continue with sort in case it's needed.If you want this to be as random as the native implementations of JavaScript's Math.random() will allow, you could use something like the following, which also has the advantages of leaving the original array untouched and only randomizing as much of the array as required:
function getRandomArrayElements(arr, count) {
var shuffled = arr.slice(0), i = arr.length, min = i - count, temp, index;
while (i-- > min) {
index = Math.floor((i + 1) * Math.random());
temp = shuffled[index];
shuffled[index] = shuffled[i];
shuffled[i] = temp;
}
return shuffled.slice(min);
}
var numbers = ['1','2','4','5','6','7','8','9','10'];
alert( getRandomArrayElements(numbers, 4) );
//return a random integer between 0 and 10
document.write(Math.floor(Math.random()*11));
document.write( numbers[ (Math.floor(Math.random()*11) ] ] ); which becomes increasingly important if the numbers array doesn't contain something as trivial as 1-10.
var numbers = new Array('1','2','4','5','6','7','8','9','10');
document.write(numbers[Math.floor(Math.random()*numbers.length)]);
var numbers = ['1', ...];.