Take a string and invert the case of each character. If the English characters in the string are wrapped between numbers then switch the numbers and if there is any other character then do not switch them.

StringChallenge.js

function StringChallenge(str) { 

  // code goes here
  let result = ""
  str = reversing(str)
  for (let i = 0; i < str.length; i++) {
      let current = str[i].charCodeAt(0)
    if (current >= 65 && current <= 90) {
      result = result + str[i].toLowerCase()
    } else if (current >= 97 && current <= 122) {
      result = result + str[i].toUpperCase()
    } else {
        result = result + str[i]
    }


  }
  return result; 

}
function reversing(str) {
    let result = ""
    let checkArr = []
    for (let i = 0; i < str.length; i++) {
        let current = str[i].charCodeAt(0)
        if (current >= 48 && current <=57) {
            checkArr.push(str[i])
            for (let j = i+1; j < str.length; j++) {
                let currentJ = str[j].charCodeAt(0)
                if ((currentJ >= 65 && currentJ <= 90) || (currentJ >= 97 && currentJ <= 122)) {
                    checkArr.push(str[j])
                } else if (currentJ >= 48 && currentJ <=57) {
                    checkArr.push(str[j])
                    let temp = checkArr.pop()
                    checkArr.push(checkArr[0])
                    checkArr[0] = temp
                    console.log(checkArr)
                    checkArr = checkArr.join('')
                    result = result + checkArr
                    i = j
                    checkArr = []
                } else {
                    checkArr.push(str[j])
                    checkArr = checkArr.join('')
                    result = result + checkArr
                    i = j
                    checkArr=[]
                }
            }
            
        } else {
            result = result + str[i]
        }
    }
    return result
}


console.log(StringChallenge("Hello 3d4jrm -5"))