面试-xf

FE

xf

  1. useRef和useState的区别

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    1. useState是异步的,useRef是同步的
    2. useState会触发视图更新,useRef不会
    3. useRef是引用类型，一个变了另外一个也会变

  2. Promise.all

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    Promise.all = function(promises) {
        return new Promise(function(resolve,reject) {
            if(!Array.isArray(promises)) {
                throw new Error('arguments must be a array')
            }
            let resolvedCounter = 0
            let promiseNum = promises.length
            let resolvedResult = []
            for(let i = 0; i < promiseNum; i++) {
                Promise.resolve(promises[i]).then(value => {
                    resolvedCounter++
                    resolvedResult[i] = value
                    if(resolvedCounter === promiseNum) {
                        return resolve(resolvedResult)
                    }
                }, error => {
                    return reject(error)
                })
            }
        })
    }

  3. React高阶组件的概念以及出现的问题

  4. vue和react的区别