在javascript中文本字符串内的数字加1

Question

I have the following variable in JavaScript:

var variable = "a=1; b=2; c=14;"

How can I change b=2 to b=3 , b=4345 to b=4346 , so adding 1 to the number after b= ?

Answer 1

You can do the following:

var variable = "a=1; b=2; c=14;"

function incB(str) {
  var re = /(.*b=)(\d+)(.*)/, // split the string to the whole match and 3 groups
      a = re.exec(str); // <- ["a=1; b=2; c=14;", "a=1; b=", "2", "; c=14;"]
  return a[1] + (parseInt(a[2], 10)+1) + a[3];
}

variable = incB(variable); // <- variable will be "a=1; b=3; c=14;"

Answer 2

It may be a bit messy but you can easily utilize the .split() function. Here's an example :

var num = "a=1; b=2;";
var indSection = num.split(";");
var b = indSection[1].split("=");
document.write(++b[1]);

Answer 3

You can use split() function twice - first to separate those letters with their values and second time on those separated parts to separate letter from value. After that you can add 1 to each number and build the string again by concatenating all those parts.

You can also use regular expressions .

Answer 4

Could use a regular expression to parse the value out, and replace the original string with the new value, something like this:

var variable = "a=1; b=2; c=14;"
var reg = /b=([0-9])+/;
var i = parseInt(reg.exec(variable)[1]);

i++;

variable = variable.replace(reg, "b="+i);
console.log(variable);

Answer 5

This should do it:

variable = variable.replace(/(b=)(\d+)(?=;)/g, function(_, pref, num) {
    return pref + (+num + 1);
});

Answer 6

I am against writting code, so here are some hints:

1. remove all whitespaces str = str.replace(/\\s/g,"");
2. create an array arr = str.split(";");
3. loop on all elements of the array for(i=0, len=arr.length; i<len; i++)
4. assing tmp to arr[i].split("=")[1] Note: [1] takes the right part, [0] the left part
5. change tmp type from string to number with tmp = tmp*1
6. update arr[i] with arr[i]=arr[i].split("=")[0]+""+(tmp+1)
7. join arr.join(" ;") to create your string again

It seems you only want to change b= , so inside the loop, make an if check on the left part and test it against "b" , however it would be easier to split by ;b= or ; b= ; b= , then take the right part, then split it by ; and take the left part, etc, etc. Like this answer .

Answer 7

You could split the string on 'b=' and the first following semicolon, use parseInt() on b and glue it all back together.

var splitted = variable.split('b=');
var begin = splitted[0];                   //everything up to b=
var end = splitted[1];                     //everything from b= on
var b = parseInt(end.substr(0, end.indexOf(';')))+1;   //b+1
variable = begin+"b="+b+end.substr(end.indexOf(';'));