Being able to easily generate random strings is great, but what if you want to specify your own characters. For example, suppose you want to visualize flipping a coin to produce entropy of 10 bits.

```js

let random = new Random(charSet2)

let flips = random.string(10)

As another example, we saw in [Character Sets](#CharacterSets) the default characters for CharSet 16 are **0123456789abcdef**. Suppose you like uppercase hexadecimal letters instead.

```js

let random = new Random('0123456789ABCDEF')

let string = random.string(48)

The 3rd option above will throw an `Error` if the characters string isn't appropriate.

```js

try {

let random = new Random('123456')

Compare that to the `entropy-string` scheme. For the example above, slicing off 5 bits at a time requires a total of 80 bits (10 bytes). Creating the same strings as above, `entropy-string` uses 80 bits of randomness per string with no wasted bits. In general, the `entropy-string` scheme can waste up to 7 bits per string, but that's the worst case scenario and that's *per string*, not *per character*!

```js

let random = new Random()

let string = random.string(80)

```js

let bits = Entropy.bitsWithPowers(6,9)

let random = new Random()

"require": "babel-core/register"

},

"devDependencies": {

"babel-cli": "^6.4.0",

"babel-core": "^6.4.0",

"babel-plugin-transform-runtime": "^6.4.3",