Random in JS

We will use Math.random() function. When you use this function you will get numbers between [0, 1) non-inclusive of 1. 

 

var random = Math.random(); 

You will get large floating point number when you print 'random' variable. For getting number which are between range of 1 & 10 you can use Math.floor() function.

 

var random = Math.floor(Math.random() * 10) + 1;

 

For getting numbers in range of 1 to 100

 

var random = Math.floor(Math.random() * 100) + 1;

Now for random Upper Case letter :

 

var randomUpper = Math.floor(Math.random() * 26) +65;

 

then you will need to convert this integer into char & you can do this by String.fromCharCode() function.

For selecting random element from array :

 

var arr = ["@", "!", "#", "*", "%", "&", "{", ":", "?", "]"];

var randomSymbol = arr[Math.floor(Math.random() * 10)];

console.log(randomSymbol);

<script>
  var random = Math.floor(Math.random() * 10) + 1;
  console.log(random);

  var randomUpper = Math.floor(Math.random() * 26) +65;
  console.log(String.fromCharCode(randomUpper));

  var arr = ["@", "!", "#", "*", "%", "&", "{", ":", "?", "]"];
  
  var randomSymbol = arr[Math.floor(Math.random() * 10)];
  console.log(randomSymbol);
</script>