npm i --save express express-graphql graphql cors
var express = require('express');
var graphqlHTTP = require('express-graphql');
const {buildSchema} = require('graphql');
const cors = require('cors'); // 用来解决跨域问题
// 创建 schema，需要注意到：// 1. 感叹号！代表 not-null
// 2. rollDice 接受参数
const schema = buildSchema(`
type Query {
username: String
age: Int!
}
`)
const root = {username: () => {return '李华'},
age: () => {return Math.ceil(Math.random() * 100)
},
}
const app = express();
app.use(cors());
app.use('/graphql', graphqlHTTP({
schema: schema,
rootValue: root,
graphiql: true
}))
app.listen(3300);
console.log('Running a GraphQL API server at http://localhost:3300/graphql')
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>graphql demo</title>
</head>
<body>
<button class="test"> 获取当前用户数据 </button>
<p class="username"></p>
<p class="age"></p>
</body>
<script>
var test = document.querySelector('.test');
test.onclick = function () {var username = document.querySelector('.username');
var age = document.querySelector('.age');
fetch('http://localhost:3300/graphql', {
headers: {
'Content-Type': 'application/json',
'Accept': 'application/json'
},
method: 'POST',
body: JSON.stringify({
query: `{
username,
age,
}`
}),
mode: 'cors' // no-cors, cors, *same-origin
})
.then(function (response) {return response.json();
})
.then(function (res) {console.log('返回结果', res);
username.innerHTML = ` 姓名：${res.data.username}`;
age.innerHTML = ` 年龄：${res.data.age}`
})
.catch(err => {console.error('错误', err);
});
}
</script>
</html>