JavaScript：查找字符串中最大的单词

Question

This is my snippet. I feel this code satisfies the algorithm, but it does not pass. What could be the possible reason?

function findLongestWord(str, separator) {
    var splitString = str.split(separator);
    for (var i = 1; i <= splitString.length; i++) {
        for (j = 1; j < splitString[i].length; j++) {
            while (j === ' ') {
                return j;
            }
        }
    }
    var greater;
    if (j > greater) {
        greater = j;
    }
    return greater;
}

findLongestWord("The quick brown fox jumped over the lazy dog", ' ');

Answer 1

Here's your code with explanation and some changes to make it work

 function findLongestWord(str, separator) { var splitString = str.split(separator); // Define it as empty string var greater = ''; // Start looping from 0th index upto the length for (var i = 0; i < splitString.length; i++) { for (j = 0; j < splitString[i].length; j++) { // Don't know what this is // `j` is the index, ie number, it cannot be equal to ` ` // I guess this is confused with the separator // This can be removed without any problem while (j === ' ') { return j; } // No use code } // Here `j` is the length of the word // Compare it with the length of greater word if (j > greater.length) { // Update the greater to current `i` string greater = splitString[i]; } } // Return greater string. return greater; } var longestWord = findLongestWord("The quick brown fox jumped over the lazy dog", ' '); document.body.innerHTML = 'Longest Word: ' + longestWord; 

---

The same code with little optimizations can be re-written as

 function findLongestWord(str, separator) { var splitString = str.split(separator); // Define it as empty string var greater = ''; for (var i = 0, len = splitString.length; i < len; i++) { if (splitString[i].length > greater.length) { // Update the greater to current `i` string greater = splitString[i]; } } return greater; } var longestWord = findLongestWord("The quick brown fox jumped over the lazy dog", ' '); document.body.innerHTML = 'Longest Word: ' + longestWord; console.log(longestWord); 

My Solution using ES6

You can use Array#reduce and Arrow functions . For same code in ES5 check this answer by @gurvinder372

str.split(' ').reduce((x, y) => x.length > y.length ? x : y);

 function findLongestWord(str, separator) { return str.split(' ').reduce((x, y) => x.length > y.length ? x : y); } var longestWord = findLongestWord("The quick brown fox jumped over the lazy dog", ' '); document.body.innerHTML = 'Longest Word: ' + longestWord; console.log(longestWord); 

Answer 2

Try this fiddle

 function findLongestWord(str, separator) { return str.split(separator).reduce(function (previousValue, currentValue) { return previousValue.length < currentValue.length ? currentValue : previousValue; }); } var longestWord = findLongestWord("The quick brown fox jumped over the lazy dog", ' '); console.log(longestWord); document.body.innerHTML = longestWord; 

Answer 3

Please try this:

function findLongestWord(str, separator) {
    var splitString = str.split(separator);  
    var greater = splitString[0];
    for (var i = 1; i < splitString.length; i++) {
        if(greater.length < splitString[i].length){
        greater = splitString[i]
      }
    }  
    return greater;
}

findLongestWord("The quick brown fox jumped over the lazy dog", ' ');

Answer 4

Javascript index starts from 0 to (length-1). After calling the split method on 'separator' argument, the words are stored in the splitString and indexed from 0 to (length-1). To find the longest word, before starting the loop we may safely assume that the first word is the longest. Then we can iterate over the words to check if any one is longer than this. If we find one, we can update our longest word. Your inner loop is redundant and the code can be write like this-

function findLongestWord(str, separator) {
var splitString = str.split(separator);
var greater = splitString[0];
for (var i = 1; i < splitString.length; i++) {
    if(greater.length < splitString[i].length)
    {
        greater = splitString[i];
    }
}
return greater; 
}
findLongestWord("The quick brown fox jumped over the lazy dog", ' ');

NB: If there are more than one word with the longest length, using this algorithm you will always find the first one searching from left to right. If you want the last one just change in if condition in the loop like this-

if(greater.length <= splitString[i].length)