node中toString() JSON.parse() JSON.stringify()的区别

node.js JSON对象和string的相互转化

JSON.parse(): 将一个字符串对象转化为json对象

ag:

const person = {
    name: "jack",
    age: 12,
    gender: "male"
}

console.log(JSON.stringify(person)) 
输出结果为： {"name":"jack","age":12,"gender":"male"}

JSON.stringify() 将一个json对象转化为字符串

ag：

const personString = `{
    "name":"jack",
    "age":12,
    "gender":"male"
}`
console.log(JSON.parse(personString)) 
输出结果为：{ name: 'jack', age: 12, gender: 'male' }

toString() 将buffer转换成字符串

ag:

const promise = new Promise((resolve, reject) => {
        const fullFilename = path.resolve(__dirname, "files", fileName)
        fs.readFile(fullFilename, (err, data) => {
            if(err) {
                reject(err)
                return
            }
            resolve(
            	// 由于readFile读取到的内容为buffer，toString()将其转化为字符串
                JSON.parse(data.toString())
            )
        })
    })