Comparing length of strings in an array?-CodePudding

Hi I'm trying to compare the length of each word in a sentence. I converted this sentence into an array but then I'm lost in my codes. I tried 2 methods - for loop and reduce(), but neither worked. What happened in my code?

Reduce() => This one gave me undefined when I try to run the function. I gathered it's because of the max.length/word.length, but how can I turn my string into length using reduce()?

function findLongestWordLength(str) {
  let brokenDown = str.split(' ')
  
  brokenDown.reduce((max, word) => {
    return Math.max(max.length, word.length)
  })
}

findLongestWordLength("The quick brown fox jumped over the lazy dog");

For loop => This one gave me the length of the first word rather than the maxLength. I'm guessing probably because my var strLength is not an array, but how to make it into an array containing the length of each index?

function findLongestWordLength(str) {
  let brokenDown = str.split(' ')
  for(let i = 0; i < brokenDown.length; i  ) {
    var strLength = brokenDown[i].length
  }
  return Math.max(strLength)
}

findLongestWordLength("The quick brown fox jumped over the lazy dog");

I know this should be very basic and simple and i can't wrap my head around what went wrong here.

CodePudding user response：

In the second approach you posted, you aren't setting the max properly. You are setting a variable called strLength, but your Math.max is outside the loop. So you will never get the maximum value unless it happens to be the last word in the array.

function findLongestWordLength(str) {
  let brokenDown = str.split(' ')
  let mxLen = 0
  for(let i = 0; i < brokenDown.length; i  ) {
    mxLen = Math.max(mxLen, brokenDown[i].length);
  }
  return mxLen
}

CodePudding user response：

const maxLength = (str) => {
  const words = str.split(' ');
  const lengths = words.map((word) => word.length);
  return Math.max(...lengths);
}
console.log(maxLength('The quick brown fox jumped over the lazy dog'));

CodePudding user response：

If you want to use the Math.max approach, first extract he lengths of each word and then pass those to the Math.max.

function findLongestWordLength(str) {
  let brokenDown = str.split(' ')
  let lengths = brokenDown.map(word => word.length);

  return Math.max(...lengths);
}

console.log(findLongestWordLength("The quick brown fox jumped over the lazy dog"));

If you want to go the for loop approach, you will have to keep a maxLength while looping, and update it as the loop encounters longer words.

function findLongestWordLength(str) {
  let brokenDown = str.split(' ')
  let maxLength = 0;
  for (let i = 0; i < brokenDown.length; i  ) {
    const wordLength = brokenDown[i].length;
    if (wordLength > maxLength) {
      maxLength = wordLength;
    }
  }
  return maxLength;
}

console.log(findLongestWordLength("The quick brown fox jumped over the lazy dog"));

CodePudding user response：

not so hard to do...

const findLongestWordLength = str =>
  str.split(' ').reduce((r,s)=>Math.max(r,s.length), 0)



console.log( findLongestWordLength("The quick brown fox jumped over the lazy dog") )