"删除最后一个特殊字符 javascript 之后的所有字符"

Question

I have the following string.

var string  = "Welcome, to, this, site";

I would like to remove all characters after the last comma, so that the string becomes

var string  = "Welcome, to, this";

How do I go about it in Javascript? I have tried,

var string = "Welcome, to, this, site";
string = s.substring(0, string.indexOf(','));

but this removes all characters after the first comma.

Answer 1

你需要的是lastIndexOf：

string = s.substring(0, string.lastIndexOf('?'));

Answer 2

you can use split and splice to achieve the result as below.

var string  = "Welcome, to, this, site";
string = string.split(',')
string.splice(-1) //Take out the last element of array
var output = string.join(',')
console.log(output) //"welcome, to, this"

Answer 3

There's a String.prototype.lastIndexOf(substring) method, you can just use that in replacement of String.prototype.indexOf(substring) :

var delimiter = ",";
if (inputString.includes(delimiter)) {
    result = inputString.substring(0, inputString.lastIndexOf(delimiter));
} else {
    result = inputString;
}

Alternatives would include Madara Uchiha 's suggestion :

var delimiter = ",";
var parts = inputString.split(delimiter);
if(parts.length > 0) { parts.pop(); }
result = parts.join(delimiter);

Or the use of regular expressions :

result = inputString.replace(/,[^,]*$/, "");

Answer 4

Try this

var string  = "Welcome, to, this, site";
var ss = string.split(",");
var newstr = "";
for(var i=0;i<ss.length-1;i++){
  if (i == ss.length-2)
      newstr += ss[i];
  else
      newstr += ss[i]+", ";
}
alert(newstr);