如何删除for循环中的最后一个逗号？

Question

function currentLine(katzDeliLine) {
    if (katzDeliLine.length > 0) {
        var textToPrint = "The line is currently: "

        for (var crrLine = 0; crrLine < katzDeliLine.length; crrLine++) {

            textToPrint = textToPrint + (crrLine + 1) + ". " + katzDeliLine[crrLine] + ","

        }


        return textToPrint;
    } else {
        return "The line is empty"
    }
}

var lineofpeople = ["katrina", "kevin", "vincent"]

Output is: The line is currently: 1. katrina, 2. kevin, 3. vincent,

I'm trying to get rid of the last comma after 'vincent'

I tried an if statement, and I also tried the .join() method. I don't know how to implement them in the code.

Answer 1

You could map the leading numbers with the value and join the array with comma.

 function currentLine(array) { return array.length ? `The line is currently: ${array.map((v, i) => `${i + 1}. ${v}`).join(', ')}.` : "The line is empty."; } var lineofpeople = ["katrina", "kevin", "vincent"]; console.log(currentLine(lineofpeople)); console.log(currentLine([])); 

Answer 2

An easy solution is using template literals and join() .

Here you should pay attention that it's not single quote but a backtick .

 var lineofpeople = ["katrina", "kevin", "vincent"] const emptyLine = [] // Using arrow function; the code is short const currentLine = (line) => { return !line.length ? 'The line is empty' : `The line is currently: ${line.map((e, i) => `${i + 1}. ${e}`).join(', ')}` } console.log(currentLine(lineofpeople)) // expected: The line is currently: 1. katrina, 2. kevin, 3. vincent console.log(currentLine(emptyLine)) // expected: "The line is empty" 

Answer 3

Remove the last part of the returned string using textToPrint.slice(0,-1)

function currentLine(katzDeliLine) {
   if (katzDeliLine.length > 0) {
   var textToPrint = "The line is currently: "  

   for (var crrLine = 0;  crrLine < katzDeliLine.length; crrLine++) {
     textToPrint = textToPrint + (crrLine + 1)+". " +katzDeliLine[crrLine]+","
   }

   return textToPrint.slice(0,-1);
   } 
   else {
      return "The line is empty"
   }
}

 var lineofpeople = ["katrina", "kevin", "vincent"]
 console.log(currentLine(lineofpeople));

Answer 4

function currentLine(katzDeliLine) {
    if (katzDeliLine.length > 0) {
        var textToPrint = "The line is currently: "  

        for (var crrLine = 0;  crrLine < katzDeliLine.length; crrLine++) {

        textToPrint = textToPrint + (crrLine + 1)+". " 
        +katzDeliLine[crrLine]+","

}


return textToPrint.replace(/,\s*$/, "");
} else {
return "The line is empty"
}
}

var lineofpeople = ["katrina", "kevin", "vincent"]
console.log(currentLine(lineofpeople));

Answer 5

You can use regex to remove the last comma

$ is for matching the end of the string

 let line = 'string1, string2, string3, string4, string5,' console.log(line.replace(/,$/g,'')) 

Answer 6

Just check if the current index is the last one, if it is, don't add a comma:

for (var crrLine = 0; crrLine < katzDeliLine.length; crrLine++) {

        textToPrint = textToPrint + (crrLine + 1) + ". " + katzDeliLine[crrLine] + (crrLine != (katzDeliLine.length - 1) ? "," : "")

    }