My code reads a line from a file and replaces numbers of length 3 to 18 digits.
The thing is I don't want to match numbers that follow the string DOM: (white space after colon).
For example:
match: tttt 23456789 dkdkd
match: 6783456789 dkdkd DOM:
no match: DOM: 23456789 dkdkd
no match: dhdhd DOM: 23456789 dkdkd
no match: DOM: 2789 dkdkd DOM: 34567896
I have tried using negative look-ahead: .*(?!DOM: )[0-9]{3,18}
But it doesn't work, please help.
You can't since the lookbehind isn't available in javascript.
The workaround is to use a function as replacement with the replace method:
yourstr = yourstr.replace(/\b(DOM: )?\d{3,18}\b/g, function (m, g) {
return g ? m : 'what you want'; });
A usual approach to mimick a lookbehind where a lookahead is not necessary (and here, a lookahead is not used), is through reversal. You reverse both the input string, the regex pattern where you can thus use a lookahead instead of a lookbehind, and then the results:
function revStr(str) {
return str.split('').reverse().join('');
}
var s = ["tttt 23456789 dkdkd", "6783456789 dkdkd DOM:",
"DOM: 23456789 dkdkd", "dhdhd DOM: 23456789 dkdkd", "DOM: 2789 dkdkd DOM: 34567896"];
var rex = /\b[0-9]{3,18}\b(?!\s*:MOD\b)/g; // Regex for matching reversed numbers
var results = []; // Array for results
s.forEach(function(t) { // Test each string
m = revStr(t).match(rex); // Collect all matches
if (m) { // If we have a match
m.forEach(function(h) {
results.push(revStr(h)); // Reverse each match value and add
});
}
}
);
document.body.innerHTML = "<pre>" + JSON.stringify(results, 0, 4) + "</pre>";