text: /*
  From this lesson, we begin to learn about String objects.
  
  First of all, we have a look at the attributes of String: length. Use StringObject.length to get the length of a string, like this:
  
  var str="dsfsdwesdfsadfwerfsdfsdfsdfsdfsdf";
  console.log(str.length)  //output: 33
  
  Secondly, a string can be like an array. each character in a string has an index. We can use the index to access this character. like this:
  
  var str="codewars";
  for (var i=0;i<str.length;i++) console.log(str[i])
  //output:
  c
  o
  d
  e
  w
  a
  r
  s
  
  String Object has a lot of methods, many of these methods are used for web page text style and color modification. These methods are rarely used in programming and some of they are deprecated now. So we will omit the learning of these methods. These methods are:
  
  anchor()    Create HTML anchor.
  big()       Display a string in a large font.
  blink()     Display flashing string.
  bold()      Use bold display string.
  fixed()     Using a typewriter text display string.
  fontcolor() Displays a string using the specified color.
  fontsize()  Displays a string using the specified size.
  italics()   Use italics string.
  link()      Display a string as a link.
  small()     Use small size to display string.
  strike()    Use the delete line to display the string.
  sub()       Display the string as a subscript.
  sup()       Display the string as a superscript.
  
  This time we learn three methods that used to obtain the substring of the string:slice() substring() and substr(). Their usage:
  
  StringObject.slice(startindex,endindex)
  StringObject.substring(startindex,endindex)
  StringObject.substr(startindex,length)
  
  Here we use some examples to illustrate their usage and difference:
  
  var str="Hello World!";
  console.log(str.slice(6))
  console.log(str.substring(6))
  console.log(str.substr(6))
  //output:
  World!
  World!
  World!
  
  We can see, the first parameter startindex can not be omitted, it represents the beginning of the interception of the string. Second parameter can be omitted, the three method will intercept the string to the end of the string. Look at the following example:
  
  var str="Hello World!";
  console.log(str.slice(0,5))
  console.log(str.substring(0,5))
  console.log(str.substr(0,5))
  //output:
  Hello
  Hello
  Hello
  
  We can see, When the startindex is 0, the results obtained by the three methods are the same. But in fact, their operations are different. slice() and substring() intercepted characters from index0 to index5 (not including index5). substr operation is to start from the index0, the interception of a substring of length 5. Look at the following example:
  
  var str="Hello beautiful World!";
  console.log(str.slice(6,16))
  console.log(str.substring(6,16))
  console.log(str.substr(6,9))
  //output:
  beautiful 
  beautiful 
  beautiful
  
  We can see, In order to intercept the same string "beautiful", they use different parameters. Looks like substring and slice usage is similar, what is the difference between them? Look at the following example:
  
  var str="Hello beautiful World!";
  console.log(str.slice(16,21))
  console.log(str.substring(16,21))
  console.log(str.slice(16,-1))
  //output:
  World
  World
  World
  
  From this example we can see that the parameters of the slice() can be a negative number. Negative meaning is starting from the right. -1 is first position from the right(at the end of that string).
  
  In a word, for silce() and substring(), we usually choose to use slice(), because it is more flexible and simple. We can choose to use them according to different needs.
  
  Ok, lesson is over. let's us do some task.
  Task
  
  Coding in function cutIt, function accept 1 parameter:arr. arr is a string array.
  
  The first mission: Traversing arr, find the shortest string length.
  
  The second mission: Traversing arr again, intercept all strings to the shortest string length(Start from index0). you can use one of slice() substring() or substr() do it. return the result after finished the work.
  
  for example:
  
  cutIt(["ab","cde","fgh"]) should return ["ab","cd","fg"]
  cutIt(["abc","defgh","ijklmn"]) should return ["abc","def","ijk"]
  cutIt(["codewars","javascript","java"]) should return ["code","java","java"]
  */
  
  function cutIt(arr) {
    var minLength = Math.min(...arr.map((str) => str.length));
    return arr.map((str) => str.slice(0, minLength));
  }