Common algorithm questions for front-end interviews in 2018

This time I bring you common algorithm questions for front-end interviews in 2018. What are the precautions for front-end interviews in 2018? Here are practical cases, let’s take a look.

[Related recommendations: Front-end interview questions(2020)]

1ObjectConvert to array

var obj={  0:'我',  1:'的',  2:'妈',  3:'呀',  length:4}//obj格式必须是类似数组的格式（键值是索引，具有length属性）var _slice=[].slice;var objArr=_slice.call(obj);

2. Statistics A stringThe most frequent letters

function countMost(str) {  const objCount = {};
  str = str.split(&#39;&#39;).sort().join(&#39;&#39;);  for(let i=0; i<str.length; i++) {    let lastIndex = str.lastIndexOf(str[i]);
    num = lastIndex - i + 1;
    objCount[str[i]] = num;
    i = lastIndex;
  }  let maxStr = [],
      maxValue = 1;  for(let p in objCount) {    if(objCount[p] > maxValue) {
      maxStr = [];
      maxStr.push(p);
      maxValue = objCount[p];
    }else if(objCount[p] == maxValue){
      maxStr.push(p);
    }
  }  return maxStr.length == 1? maxStr[0] : maxStr;
}console.log(countMost(&#39;afjghdfffffraaaasdddddenas&#39;));

3. Find the maximum difference between the following positive arrays

const arr = [10,5,11,7,8,9];function getMaxProfit(arr) {  let max = arr[0],
      min = arr[0];  for(let i=1; i<arr.length; i++) {
    max = Math.max(max,arr[i]);
    min = Math.min(min,arr[i]);
  }  return max - min;
}console.log(getMaxProfit(arr));

4. Get the maximum or minimum value in the array

function maxAndMin(arr){  return {    max:Math.max.apply(null,arr.join(',').split(',')),    min:Math.min.apply(null,arr.join(',').split(','))
  }
}var arr = [22,0,[3,4,2,55]];
maxAndMin(arr).max;// 55maxAndMin(arr).min;// 0

5. Generate a random alphanumeric string of specified length

function getRandomStr(len) {  var str = "";  for( ; str.length < len; str += Math.random().toString(36).substr(2));  return str.substr(0, len);
}

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to the php Chinese websiteOthersrelated articles!

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