JS replace with regular expression

Question

Need a regular expression. If I want to replace "abcdf" with "PPP" in

XabcdfX is xxxxxxx. <MabcdfM> has xxxxx. abcdf is xxxxxxx. <FabcdfF> zxabcdf abcdf.

then the expected output

XPPPX is xxxxxxx. <MabcdfM> has xxxxx. PPP is xxxxxxx. <FabcdfF> zxPPP PPP.

abcdf can be a whole string or even can be a substring. It will be only alphanumeric. It can only be replaced when it does not come between < >.

I need to do it using javascript replace method. Please help me.

Unlike Switz I think the question is pretty clear, but I'd like to see what you've tried so far. Also, what if the input string has something like "The number 3 < 5. abcdf But 6 > 2." — nnnnnn
– nnnnnn, Commented Nov 23, 2011 at 10:55
This question looks like this other one: stackoverflow.com/questions/8214777/… — Rodolphe
– Rodolphe, Commented Nov 23, 2011 at 11:01

Kobi · Accepted Answer · 2011-11-23 11:02:11Z

3

You can do it using a callback to replace:

s = s.replace(/abcdf|(<[^>]*>)/g, function(g0,g1){return g1 ? g1: 'PPP';});

Working Example: http://jsbin.com/abakax

Obviously, this will fail if you have nested or non-matching pairs of Angle brackets.

answered Nov 23, 2011 at 11:02

Kobi

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georg · Accepted Answer · 2011-11-23 11:07:57Z

1

Assuming your "tags" cannot be nested, you can use a lookahead assertion:

s.replace(/abcdf(?=[^<>]*(<|$))/g, "PPP")

answered Nov 23, 2011 at 11:07

georg

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Hachi · Accepted Answer · 2011-11-23 11:04:52Z

0

if you can be sure, that there is nothing like >, I would use the indexOf-function iteratively rather than using a regex:

index = string.indexOf("<", lastIndex);
index = string.indexOf(">", index);
index = string.indexOf("abcd", index);
string = string.substring(0, index)+"PPP"+string.substring(index+4);

answered Nov 23, 2011 at 11:04

Hachi

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just somebody · Accepted Answer · 2011-11-23 12:02:36Z

var collect = function (s, re)
{
  var rv = [];
  for (var m; m = re.exec(s); rv.push(m));
  return rv;
}
var s = "XabcdfX is xxxxxxx. <MabcdfM> has xxxxx. abcdf is xxxxxxx. <FabcdfF> zxabcdf abcdf."
var tags = collect(s, /<[^>]*>/g);
var matches = collect(s, /abcdf/g);

console.log("INPUT:", s)

var r = s

MATCH: for (var i = 0, j = 0; i < matches.length; ++i) {
  var m = matches[i]
  var mbeg = m.index
  var mend = mbeg + m[0].length
  TAG: for (; j < tags.length; ++j) {
    var t = tags[j]
    var tbeg = t.index
    var tend = tbeg + t[0].length
    if (tend < mbeg)
      continue TAG
    if (tbeg < mbeg && tend > mend)
      continue MATCH
    if (tbeg > mbeg)
      break TAG
  }
  r = r.substr(0, mbeg) + m[0].toUpperCase() + r.substr(mbeg + m[0].length)
}
console.log("RESULT:", r)

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