查找数组中最长的字符串

时间：2011-06-29 13:16:32

标签： javascript

是否有一种简短的方法可以找到字符串数组中最长的字符串？

像arr.Max(x => x.Length);？

之类的东西

22 个答案:

答案 0 :(得分：160)

var longest = arr.sort(function (a, b) { return b.length - a.length; })[0];

可能效率更高，但仅在Javascript 1.8/ECMAScript 5后可用，默认情况下在旧浏览器中不可用：

var longest = arr.reduce(function (a, b) { return a.length > b.length ? a : b; });

答案 1 :(得分：23)

我会做这样的事情

var arr = ['first item', 'second item is longer than the third one', 
           'third longish item'];

var lgth = 0;
var longest;

for(var i=0; i < arr.length; i++){
    if(arr[i].length > lgth){
        var lgth = arr[i].length;
        longest = arr[i];
    }      
} 

alert(longest);

http://jsfiddle.net/jasongennaro/MLqLq/

答案 2 :(得分：22)

对旧问题的新答案：在ES6中你可以做得更短：

Math.max(...(x.map(el => el.length)));

答案 3 :(得分：4)

var arr = [ 'fdgdfgdfg', 'gdfgf', 'gdfgdfhawsdgd', 'gdf', 'gdfhdfhjurvweadsd' ];
arr.sort(function (a, b) { return b.length - a.length })[0];

答案 4 :(得分：4)

使用Array.prototype - （排序类似于@katsPaugh和@deceze在我做小提琴时发布的内容）

DEMO HERE 

var arr = [
    "2 --",
    "3 ---",
    "4 ----",
    "1 -",
    "5 -----"
];

Array.prototype.longest=function() {
    return this.sort(
      function(a,b) {  
        if (a.length > b.length) return -1;
        if (a.length < b.length) return 1;
          return 0
      }
    )[0];
}
alert(arr.longest());

答案 5 :(得分：4)

我看到最短的解决方案

function findLong(s){
  return Math.max.apply(null, s.split(' ').map(w => w.length));
}

答案 6 :(得分：3)

在ES6中，这可以通过reduce()复杂度的O(n)调用来完成，而不是使用sort()的{​​{1}}解决方案：

O(nlogn)

答案 7 :(得分：3)

我提供了一种功能+递归方法。查看评论以了解其工作原理：

const input1 = ['a', 'aa', 'aaa']
const input2 = ['asdf', 'qwer', 'zxcv']
const input3 = ['asdfasdf fdasdf a sd f', ' asdfsdf', 'asdfasdfds', 'asdfsdf', 'asdfsdaf']
const input4 = ['ddd', 'dddddddd', 'dddd', 'ddddd', 'ddd', 'dd', 'd', 'd', 'dddddddddddd']

// Outputs which words has the greater length
// greatestWord :: String -> String -> String
const greatestWord = x => y => 
      x.length > y.length ? x : y
      
// Recursively outputs the first longest word in a series
// longestRec :: String -> [String] -> String
const longestRec = longestWord => ([ nextWord, ...words ]) =>
      //                                ^^^^^^^^^^^^
      // Destructuring lets us get the next word, and remaining ones!
      nextWord // <-- If next word is undefined, then it won't recurse.
        ? longestRec (greatestWord (nextWord) (longestWord)) (words) 
        : longestWord


// Outputs the first longest word in a series
// longest :: [String] -> String
const longest = longestRec ('')

const output1 = longest (input1)
const output2 = longest (input2) 
const output3 = longest (input3)
const output4 = longest (input4)

console.log ('output1: ', output1)
console.log ('output2: ', output2)
console.log ('output3: ', output3)
console.log ('output4: ', output4)

答案 8 :(得分：1)

我会做这样的事情：

function findLongestWord(str) {
var array = str.split(" ");
var maxLength=array[0].length;
for(var i=0; i < array.length; i++ ) {
if(array[i].length > maxLength) maxLength = array[i].length}
return maxLength;}

findLongestWord("What if we try a super-long word such as otorhinolaryngology");

答案 9 :(得分：1)

也许不是最快的，但肯定是可读的：

function findLongestWord(array) {
  var longestWord = "";

  array.forEach(function(word) {
    if(word.length > longestWord.length) {
      longestWord = word;
    }
  });

  return longestWord;
}

var word = findLongestWord(["The","quick","brown", "fox", "jumped", "over", "the", "lazy", "dog"]);
console.log(word); // result is "jumped"

数组函数map。

答案 10 :(得分：1)

如果您的字符串已经拆分为数组，则不需要拆分部分。

function findLongestWord(str) {
  str = str.split(' ');
  var longest = 0;

  for(var i = 0; i < str.length; i++) {
     if(str[i].length >= longest) {
       longest = str[i].length;
        } 
     }
  return longest;
}
findLongestWord("The quick brown fox jumped over the lazy dog");

答案 11 :(得分：0)

来这里求解决方法，但看不懂，贴出我的版本；

const getLongestStr = (longestStr, str) => {
  return longestStr.length > str.length ? longestStr : str;
}
var input = ['ali', 'Shahenshah', 'naqvi', 'hm'];
var longest = input.reduce(getLongestStr, "")

答案 12 :(得分：0)

function allLongestStrings(array) {
    const newArr=[];
    let temp =    Math.max(...(array.map(el => el.length)));    
     array.forEach(item => {
        if(temp == item.length){
          newArr.push(item);
        }
    });
    return newArr;
}

答案 13 :(得分：0)

这是我的简单解决方案

var arr = ["you", "are", "the", "love", "of", "my", "life"];
var sorted = arr.sort(function (a, b){
     return b.length - a.length;
});

console.log(sorted[0])

答案 14 :(得分：0)

Modern browsers support a for...of loop.在Chrome，Safari，Edge和Firefox中解决此问题的最快，最短的方法也是最清晰的：

let largest = '';
for (let item of arr) {
  if (item.length > largest.length) largest = item
}

In IE, you can use Array.forEach;比对数组进行排序或精简还更快，更清晰。

var largest = '';
arr.forEach(function(item) {
  if (item.length > largest.length) largest = item
});

答案 15 :(得分：0)

在支持ES6的同时，还重复了字符串

var allLongestStrings = arrayOfStrings => {
  let maxLng = Math.max(...arrayOfStrings.map( elem => elem.length))
  return arrayOfStrings.filter(elem => elem.length === maxLng)
}

let arrayOfStrings = ["aba", "aa", "ad", "vcd","aba"]

console.log(allLongestStrings(arrayOfStrings))

答案 16 :(得分：0)

如果您期望超过一个，这将起作用：

_.maxBy(Object.entries(_.groupBy(x, y => y.length)), y => parseInt(y[0]))[1]

它使用lodash并返回一个数组。

答案 17 :(得分：0)

function findLongestWord(str) {
  str = str.split(" ");
  var sorted = str.sort(function(prev,current){
    return prev.length - current.length;   
  });
  var index = sorted.length;
  str = sorted[index-1];
  return str;
}
findLongestWord("The quick brown fox jumped over the lazy dog");

答案 18 :(得分：0)

var longest = (arr) => {
  let sum = 0
  arr.map((e) => {
    sum = e.length > sum ? e.length : sum
  })
  return sum
}

它可以工作

答案 19 :(得分：0)

我对Jason的功能有所启发，并对其进行了一些改进，并得到了相当快速的查找器：

function timo_longest(a) {
  var c = 0, d = 0, l = 0, i = a.length;
  if (i) while (i--) {
    d = a[i].length;
    if (d > c) {
      l = i; c = d;
    }
  }
  return a[l];
}
arr=["First", "Second", "Third"];
var longest = timo_longest(arr);

速度结果：http://jsperf.com/longest-string-in-array/7

答案 20 :(得分：-1)

var array = ["hello","falsey","undefined"];
var findLongestWord = function(array){
    var longest = array.reduce(function(a,b){
    return (a.length > b.length) ? a : b;
  });
    return longest;
}
findLongestWord(array);

答案 21 :(得分：-2)

这是我在5分钟前编写的非常简单的错误代码。我没有时间修复错误，但如果你明白了，你可以改变并使用它。 

Array.prototype.MaxBy = function(fn) {        
    var max = 0;
    var element;
    for (var i = 0; i < this.length; i++) {
        var ret = fn(this[i]);
        if (ret > max) {
            max = ret;
            element = this[i];
        }
    }
    return element;
};

function showOldestPerson() {
    var array = [{ Name: "cihat", Age: 28 }, { Name: "Ali", Age: 30 }, { Name: "Kutlu", Age: 27}];

    var person = array.MaxBy(function(item) {
        return item.Age;
    });

    alert(person.Name);
}
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