最近要干的活

promise.all

promise执行过程

// promise较好的格式
promise
  .then(function(data) { //cb
    // success
  })
  .catch(function(err) {
    // error
  });

catch === then(null,(reject)=>{})

promise串行执行

const timeout = ms => new Promise((resolve, reject) => {
    setTimeout(() => {
        resolve();
    }, ms);
});

const ajax1 = () => timeout(2000).then(() => {
    console.log('1');
    return 1;
});

const ajax2 = () => timeout(1000).then(() => {
    console.log('2');
    return 2;
});

const ajax3 = () => timeout(2000).then(() => {
    console.log('3');
    return 3;
});

const mergePromise = ajaxArray => {
    // 在这里实现你的代码
    var data = [];
    var sequence = Promise.resolve();
    ajaxArray.forEach(function(item){
        sequence = sequence.then(item).then(function(res){
            data.push(res);
            return data;
        });
    })
    return sequence;
};

mergePromise([ajax1, ajax2, ajax3]).then(data => {
    console.log('done');
    console.log(data); // data 为 [1, 2, 3]
});

json.stringify()与json.parse()实现

bind实现

Function.prototype.Bind = function (context) {
    var self = this;
    //获取Bind函数从第二个参数到最后一个参数
    var args = Array.prototype.slice.call(arguments,1);

    return function(){
        //获取调用Bind时传入的参数
        var bindArgs = Array.prototype.slice.call(arguments);
        return self.apply(context,args.concat(bindArgs));
    }
}

归并排序

二叉树遍历

动态规划

二叉排序树

二分查找

function binSearch(arr,target,startIdx,endIdx) {
    let len = arr.length,
        startIndex = typeof startIdx === 'number'?startIdx:0,
        endIndex = typeof endIdx === 'number'?endIdx:len-1,
        midIndex = Math.floor((startIndex+endIndex)/2),
        midVal = arr[midIndex];
    if(startIndex>endIndex)return;
    if(midVal === target){
        return midIndex;
    }else if(midVal>target){
        return binSearch(arr,target,startIndex,midIndex-1);
    }else{
        return binSearch(arr,target,midIndex+1,endIndex);
    }
}
console.log(binSearch(arr,23));