How to create an array with random values with the help of JavaScript ?
The task is to generate an array with random values with the help of JavaScript. There are two approaches which are discussed below:
Approach 1:
- Use Math.random() and Math.floor() method to get the random values.
- Push the values one by one in the array (But this approach may generate repeated values).
Example: This example implements the above approach.
<!DOCTYPE HTML> <html> <head> <title> create an array with random values </title> </head> <body style="text-align:center;"> <h1 style="color: green"> GeeksForGeeks </h1> <p id="GFG_UP"></p> <button onclick="gfg_Run()"> Click Here </button> <p id="GFG_DOWN" style="color:green;"></p> <script> var el_up = document.getElementById("GFG_UP"); var el_down = document.getElementById("GFG_DOWN"); el_up.innerHTML = "Click on the button to generate the array."; function gfg_Run() { el_down.innerHTML = Array.from({ length: 10 }, () => Math.floor(Math.random() * 10)); } </script> </body> </html> |
Output:
-
Before clicking on the button:
-
After clicking on the button:
Approach 2:
- Create an array and put the values in it (like, 1 at index 0, 2 at index 1, 3 at index 2 in the same order by a loop.)
- Assign variable (tp) = length of the array.
- Run a loop on variable(tp).
- Inside loop use Math.random() and Math.floor() method to get the random index of the array.
- Swap this array value with the index(tp) and decrease the variable(tp) by 1.
- Run the loop until variable(tp) becomes 0.
Example: This example implements the above approach.
<!DOCTYPE HTML> <html> <head> <title> create an array with random values. </title> </head> <body style="text-align:center;"> <h1 style="color: green"> GeeksForGeeks </h1> <p id="GFG_UP"></p> <button onclick="gfg_Run()"> Click Here </button> <p id="GFG_DOWN" style="color:green;"> </p> <script> var el_up = document.getElementById("GFG_UP"); var el_down = document.getElementById("GFG_DOWN"); for (var a = [], i = 0; i < 10; ++i) a[i] = i; // Array like[1, 2, 3, 4, ...] el_up.innerHTML = "Click on the button to generate the array."; function createRandom(arr) { var tmp, cur, tp = arr.length; if (tp) // Run until tp becomes 0. while (--tp) { // Generating the random index. cur = Math.floor(Math.random() * (tp + 1)); // Getting the index(cur) value in variable(tmp). tmp = arr[cur]; // Moving the index(tp) value to index(cur). arr[cur] = arr[tp]; // Moving back the tmp value to // index(tp), Swaping is done. arr[tp] = tmp; } return arr; } function gfg_Run() { el_down.innerHTML = createRandom(a); } </script> </body> </html> |
Output:
-
Before clicking on the button:
-
After clicking on the button:
.png)
