mascara-1

来源：https://github.com/MetaMask/mascara

(beta) Add MetaMask to your dapp even if the user doesn't have the extension installed

有两种调用mascara的方法：

1）页面端

<script src="https://wallet.metamask.io/metamascara.js"></script>

在网页上调用，将得到：

因此在网页上可以通过window.metamask.createDefaultProvider()的方法来进行使用

2）后台调用（现在我使用的是这种方法）看简单使用metamascara

npm i --save metamascara

const metamask = require('metamascara')
const EthJs = require('ethjs')

// mascara will use the environmental provider if the user brings one
// in the form of metamask extension, mist or parity
// other wise it will make one for you :}

const ethereumProvider = metamask.createDefaultProvider()

const eth = new EthJs(ethereumProvider)

或者：

const metamask = require('metamascara');
const Web3 = require('web3');
const ethereumProvider = metamask.createDefaultProvider();
const web3 = new Web3(ethereumProvider);

Developing:

For development with metamask-extension/mascara to point the iframe at localhost just do:

const metamask = require('metamascara')
const ethereumProvider = metamask.createDefaultProvider({
    host: 'http://localhost:9001'
  }) // or what ever port you use

如果上面没有设置host，那就说明要使用的是网页版的metamask（https://wallet.metamask.io）。如果想要设置自己的网页版，那么就要将相应的服务端写好，并将接口设成9001，然后就可以通过设置host来进行连接了（这部分之后再讲，在这里将直接使用网页版的metamask）

How does it work and how to use it:

Mascara is an iframe that acts as a proxy between your dapp and metamask core. The metamask core is the global context housed in a service worker, it does the key management for every dapp the user visits.

然后后面分析一下代码