如何在 JavaScript 中将字符串转换为脊柱大小写？

Question

I am stuck on this coding challenge Spinal Tap Case from freeCodeCamp. Essentially I don't know how to get the last check to execute.

This is the last check: spinalCase("AllThe-small Things") should return "all-the-small-things"

And this is my code:

function spinalCase(str) {
    var outputString, 
              newstr,
              pattern1 = new RegExp(/[_\s]/, 'g'),
              pattern2 = new RegExp(/(?=[A-Z])/, 'g'),
              stringTest1 = pattern1.test(str),
              stringTest2 = pattern2.test(str);

         if(stringTest1)  {
                outputString = str.replace(pattern1, '-');
                newstr = outputString.toLowerCase();
          } else if(stringTest2) {
               str.split(/(?=[A-Z])/).join(' ');
                outputString = str.replace(pattern2, '-');
                newstr = outputString.toLowerCase();
          } else if (stringTest1 && stringTest2){
                outputString = str.replace(pattern1, '-');
                outputString = str.replace(pattern2, '-');
                newstr = outputString.toLowerCase();
          }

  return newstr;

}

I do realize the last else if condition should go first however I didn't get the syntax right.

Thanks in advance!

Answer 1

Here is how I recommend doing it:

function sp(str) {
  var spinal = str.replace(/(?!^)([A-Z])/g, ' $1')
                .replace(/[_\s]+(?=[a-zA-Z])/g, '-').toLowerCase();
  return spinal 
}

JsBin Example

as far as your code, you check for:

if test1 else if test2 , then else if test1 and test2 , the logic is not correct:

you could try to adding a !test2 or !test1 to the first if checks to get it working:

if (stringTest1 && !stringTest2)...

EDIT:

here is how you can get your code to fire in that last else if, I put a console.log in there to show you here:

JSBin Example

function spinalCase(str) {
    var outputString, 
              newstr,
              pattern1 = new RegExp(/[_\s]/, 'g'),
              pattern2 = new RegExp(/(?=[A-Z])/, 'g'),
              stringTest1 = pattern1.test(str),
              stringTest2 = pattern2.test(str);

         if(stringTest1 && !stringTest2)  {
                outputString = str.replace(pattern1, '-');
                newstr = outputString.toLowerCase();
          } else if(!stringTest1 && stringTest1) {
               str.split(/(?=[A-Z])/).join(' ');
                outputString = str.replace(pattern2, '-');
                newstr = outputString.toLowerCase();
          } else if (stringTest1 && stringTest2){
                console.log('were in the last else!!!');
                outputString = str.replace(pattern1, '-');
                outputString = str.replace(pattern2, '-');
                newstr = outputString.toLowerCase();
          }

  return newstr;

}

Answer 2

Here's my solution, simple with regex and works for all cases

function spinalCase(str) {
  return str.replace(/([A-Z])/g,' $1') /*Find all cap and add space at the start*/
        .replace(/[^A-Za-z0-9]/g,' ') /*Find all non alpha numeric and replace it with space*/
        .replace(/\s{1,}/g,"-") /*Convert all spaces to -*/
        .replace(/^\-|[\-]$/g,'') /*Slice - at the start and end*/
        .toLowerCase(); /*LowerCase it*/
}

Answer 3

here's my solution, a bit less heavy on the regex:

function spinalCase(str) {
  var newStr = str[0];

  for (var j = 1; j < str.length; j++) {
    // if not a letter make a dash
    if (str[j].search(/\W/) !== -1 || str[j] === "_") {
      newStr += "-";
    }
    // if a Capital letter is found 
    else if (str[j] === str[j].toUpperCase()) {
      // and preceded by a letter or '_'
      if (str[j-1].search(/\w/) !== -1 && str[j-1] !== "_") {
        // insert '-' and carry on
        newStr += "-";
        newStr += str[j];
      }
      else {
        newStr += str[j];
      }
    }
    else {
        newStr += str[j];
    }
  }

  newStr = newStr.toLowerCase();
  return newStr;
}

Answer 4

function spinalCase(str) {

  // any string followed by upperCase letter
  var  re = /(?=[A-Z])/g;  

  // any string followed by space and upperCase/lowerCase letter 
  var  re2=/(?=\s[A-Z]|\s[a-z])/g;

  // any string of 2 or more '-'
  var re3 = new RegExp("-{2,}", "g");

  var space = new RegExp(" ","g");
  var hyphen = new RegExp("_","g");

  str = str.replace(hyphen,"-");
  str = str.replace(re, '-');   
  str = str.replace(re2,"-");
  str = str.replace(re3,"-"); 
  str = str.replace(space,"");
  str = str.toLowerCase();
  if(str.slice(0,1)== '-'){
    str = str.replace("-","");  
  }     
  return str;
}

spinalCase('This Is Spinal Tap');

Answer 5

function spinalCase(str) {
  var newStr = '';
  var arr = str.split('');
  for (var i = 0; i < arr.length; i += 1) {
    if (i > 0) {
      if (arr[i] >= 'A' && arr[i] <= 'Z') {
        if (arr[i - 1] >= 'a' && arr[i - 1] <= 'z') {
          newStr += '-';
          newStr += arr[i].toLowerCase();
          continue;
        }
      }
      else if (arr[i] === ' ' || arr[i] === '_') {
        newStr += '-';
        continue;
      }
    }
    newStr += arr[i].toLowerCase();
  }
  return newStr;
}

spinalCase("AllThe-small Things");

Answer 6

function spinalCase(str) {
//Split the string at one of the following conditions 
        //a whitespace character [\s] is encountered
        //underscore character [_] is encountered
        //or by an uppercase letter [(?=[A-Z])]
//Join the array using a hyphen (-)
//Lowercase the whole resulting string 

   return str.split(/\s|_|(?=[A-Z])/).join('-').toLowerCase(); 

}

Answer 7

I was stuck on this too, but found a simpler solution:

 function spinalCase(str) { const regex =new RegExp(/(([AZ]|[az])[az]+)/,'g'); str=str.match(regex); return str.join('-').toLowerCase(); } console.log(spinalCase('AllThe-small things'));

Answer 8

A beginner friendly solution:

function spinalCase(str) {
//change camelCase to title case(i.e. change 'markIsHere' to 'Mark Is Here') 
    let newStr = str.replace(/([a-z])([A-Z])/g, ('$1 $2'));
//replace space with '-'
    newStr = newStr.replace(/ /g, '-');
//replace underscores with '-'
    newStr = newStr.replace(/_/g,'-');
//change the result to lowercase
    return newStr.toLowerCase()
}

Answer 9

function spinalCase(str) {

  // Create a variable for the white space and underscores
  var regex = /\s+|_+/g;

  // Replace low-upper case to low-space-uppercase
  str = str.replace(/([a-z])([A-Z])/g, '$1 $2');

  // Replace space and underscore with dashes
  return str.replace(regex, '-').toLowerCase();

}

Answer 10

function insert(arr){
    arr = arr.split("");
    for(let i in arr){
      if (/[A-Z]/.test(arr[i])&& i>0){
        arr[i] = "-" + arr[i];
      }
    }
    arr = arr.join("");
    return arr;
  }

function spinalCase(str) {
  
  str = str.split(/\s+|_/);
  str = str.map(item=>insert(item));
  str = str.join("-");
  str = str.toLowerCase();
  return str;
  
}

Answer 11

I've come up with the following. For the FCCamp purpose it works

function spinalCase(str) {
  return str
    .split(/(?=[A-Z])/)
    .join()
    .split(/[_\W+]/)
    .join(' ')
    .split(/\s+/)
    .join('-')
    .toLowerCase()
}
spinalCase("AllThe-small Things");

Answer 12

I have no illusions that anybody is going to care now ;), but I would have searched for positions in-between words, as indicated by capital letters, and placed hyphens there instead. For example:

 const spinalCase = (str) => { let regex = /(?:\\B|[ _])(?=[AZ])/g; return str.replace(regex, '-').toLowerCase(); } console.log(spinalCase('AllThe-small Things'));