In JavaScript, you can generate a random number with the Math.random() function.
Math.random() returns a random floating-point number ranging from 0 to less than 1 (inclusive of 0 and exclusive of 1)
Example 1: Generate a Random Number
// generating a random number
const a = Math.random();
console.log(a);
Output
0.5856407221615856
Here, we have declared a variable a and assigned it a random number greater than or equal to 0 and less than 1.
Note: You might get a different output in the above program as Math.random() will generate a random number.
We can use this value in the range (0,1) to find the random value between any two numbers using formula:
Math.random() * (highestNumber - lowestNumber) + lowestNumber
Example 2: Get a Random Number between 1 and 10
// generating a random number
const a = Math.random() * (10-1) + 1
console.log(`Random value between 1 and 10 is ${a}`);
Output
Random value between 1 and 10 is 7.392579122270686
This will show a random floating-point number greater than 1 and less than 10.
All the above examples give floating-point random numbers.
You can use Math.floor() to get a random integer value. Math.floor() returns the number by decreasing the value to the nearest integer value. For example,
Math.floor(5.389); // 5
Math.floor(5.9); // 5
The syntax to find the random integer value between two numbers:
Math.floor(Math.random() * (highestNumber - lowestNumber)) + lowestNumber
Example 3: Integer Value between 1 and 10
// generating a random number
const a = Math.floor(Math.random() * (10 - 1)) + 1;
console.log(`Random value between 1 and 10 is ${a}`);
Output
Random value between 1 and 10 is 2
This will show integer output between 1 (inclusive) to 10 (exclusive), i.e. (1 to 9). Here, Math.floor() is used to convert decimal to integer value.
Similarly, if you want to find the random integer in between min (inclusive) to max (inclusive), you can use the following formula:
Math.floor(Math.random() * (max - min + 1)) + min
Example 4: Integer Value between Two Numbers (Inclusive)
// input from the user
const min = parseInt(prompt("Enter a min value: "));
const max = parseInt(prompt("Enter a max value: "));
// generating a random number
const a = Math.floor(Math.random() * (max - min + 1)) + min;
// display a random number
console.log(`Random value between ${min} and ${max} is ${a}`);
Output
Enter a min value: 1 Enter a max value: 50 Random value between 1 and 50 is 47
This will show the integer output between min (inclusive) to max (inclusive).
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