big-number-input
A BigNumberInput to use with decentralized applications and React.
![devDependencies Status](https://david-dm.org/protofire/big-number-input/dev-status.svg)
The problem
You are using big integer numbers that can be expressed as smaller fractional numbers and you want users to be able to
enter them in this format. The originating use case for this library are ERC20 tokens, but a simpler example is having
some amount expressed in millions. You want the user to input 1.5
but to receive a bignumber containing 1500000
. In
this case, you can use big-number-input
with a decimals
value of 6. See Usage
below for more information.
Installation
npm install big-number-input
Usage
Import the component and pass the required props:
import React from 'react'
import { BigNumberInput } from 'big-number-input'
function App() {
const [value, setValue] = React.useState('1000000')
return (
<div>
<BigNumberInput
decimals={6}
onChange={setValue}
value={value}
/>
<div>{value || 'empty'}</div>
</div>
)
}
export default App
In this case the input value is 1000000 and the rendered value will be 1. If the user changes it to 2 in the UI the onChange will be called with 2000000.
The required props are:
decimals
: The number of decimals you want to usevalue
: A string with the raw value that will be used by the input, eg. 1000000.onChange
: A function that receives the new raw value, or an empty string when the input is empty
Then you have a bunch of optional props you can use:
autofocus
: Set to true if you want the input to obtain focus as soon as it's renderedplaceholder
: A string to use as the input's placeholderdisabled
: A boolean used to disable the inputmin
, max
and step
: The min and max values you want to use and the step used when you increase or decrease the
number with the arrow keys or by clicking the arrows in the input. These values are also strings with the raw values and are interpreted with the same number of decimals as the main value.
Using a different input component
If you want to use a different input, for example the Input
from Material UI, you can use
the renderInput
prop:
import React from 'react';
import { BigNumberInput } from 'big-number-input'
import { Input } from '@material-ui/core'
function App() {
const [value, setValue] = React.useState('')
return (
<div>
<BigNumberInput decimals={6} onChange={setValue} value={value} renderInput={
props => <Input {...props} />
}/>
<div>{value || 'empty'}</div>
</div>
);
}
Converting to and from a big number
If you want to use some big number library to store your value, you can follow an approach like this:
import React from "react";
import Big from 'big.js'
import { BigNumberInput } from "big-number-input";
function App() {
const [value, setValue] = React.useState(null);
return (
<div>
<BigNumberInput
autofocus={true}
decimals={6}
onChange={newValue => newValue ? setValue(new Big(newValue)) : setValue(null)}
value={value ? value.toString() : ''}
/>
<div>{value ? value.toString() : "empty"}</div>
</div>
);
}
Here we use null
to indicate an empty input, and a big number instance when there is something entered in the input.