Related
I have no idea why this hangs the javascript engine but it does. Anyone else have a clue?
function isEnglish(text) {
const checker = /^(\p{Emoji}|\p{ASCII})+$/u;
return !!checker.exec(text.replace(/\\n/g, ""));
}
text = `
RT #PROMOSIGROUP: FOLL TWITTER
3K:20rb
5k:30rb
10K:50rb
Foll IG aktif WW
100F:15rb
500F:50rb
1K:100rb
Jual Akun Twitter+IG
081327927525/…`
isEnglish(text);
Ok, figured it out, the "…" character causes the regex engine to spin. Anyone know why this might be?
It looks like you're isEnglish() test is supposed to return true when the source text consists solely of:
US-ASCII characters,
Emoji (not sure why this would count as "english", but whatever), and
Punctuation
and false otherwise.
I might point out that US-ASCII covers U+0000 to U+007F: that includes the C0 Control Characters (U+0000 to U+001F), as well as [DEL] (U+007F), none of which, save whitespace, are actual characters.
But, you're making a mountain out of a molehill: it will be much faster (and clearer) to just search for the first character that's not part of your desired alphabet:
function isEnglish(s) {
return !rxIsNonEnglishAlphabet.test(s);
}
// -------------------------------------------------------
// this regular expression matches characters that are NOT
// * Whitespace
// * US-ASCII (u+0000 through U+007F)
// * Emoji
// * Punctuation
// -------------------------------------------------------
const rxIsNonEnglishAlphabet = /[^\s\p{ASCII}\p{Emoji}\p{Punctuation}]/u;
It turns out that my regex turns into a big backtracking bug even though there isn't anything obvious to me that would cause that. My function now looks much different to get it to work:
function isEnglish(text) {
const ascii = /\p{ASCII}/ug;
const emoji = /\p{Emoji}/ug;
const punct = /\p{Punctuation}/ug;
text = text.replace(ascii, "");
text = text.replace(emoji, "");
text = text.replace(punct, "");
return text.length === 0;
}
I am willing to do the following:
I have :
var distance1 = "5.5 Km";
var distance2 = "5,5 Km";
//The below works as expected and returns 5.5
var finalDistance = distance1.replace( /[^\d\.]*/g, '');
//However the below doesn't and print 55 instead
distance2.replace( /[^\d\.]*/g, '');
//I've tried the below too and it throws 5,5. But I want 5.5
distance2.replace( /[^\d\.\,]*/g, '');
First, replace all occurences of , with ., then replace non-digit characters (except .) with '':
distance2 = distance2.replace( /,/g, '.').replace(/[^\d\.]+/g, '');
where:
/,/g : matches all commas ',' that will be replaced by '.'
/[^\d\.]+ : matches any sequence of non-digit and non-dot ('.') characters that will be removed (replaced by the empty string '').
The first replace transform "5,55 KM" to "5.55 KM" then the second transform the latter to "5.55".
Note: if you only have one comma, or only interested in the first encountered one, then you could use: replace(',', '.') instead of replace(/,/g, '.').
If you are using only the float representation, you could use parseFloat instead of the second replace:
var number = parseFloat(distance2.replace(/,/g, '.'));
replace works by saying "find this string and replace with this string". The first parameter is what you want to find, the second is what to replace it with. So in your code you're replacing the , with nothing:
distance2.replace( /[^\d\.]*/g, '');
It also doesn't edit the string "in-place", so you need to assign the distance2 variable to the return value. Also, for a simple job like this you don't need to use regex. You can just input a string as the first parameter and replace will find all matches for that. This is how I would do this:
distance2 = distance2.replace(',', '.');
Further reading:
https://www.w3schools.com/jsref/jsref_replace.asp
https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/String/replace
you need to reassign the replace value to the variable.
i.e.
distance2 = distance2.replace( /[^\d\.]*/g, '');
I need to do the following to a string:
Remove any punctuation (but retain spaces) (can include removal of foreign chars)
Add dashes instead of spaces
toLowercase
I'd like to be able to do this as succinctly as possible, so on one line for example.
At the moment I have:
const ele = str.replace(/[^\w\s]/, '').replace(/\s+/g, '-').toLowerCase();
Few problems I'm having. Firstly the line above is syntactically incorrect. I think it's a problem with /[^\w\s] but I am not sure what I've done wrong.
Secondly I wonder if it is possible to write a regex statement that removes the punctuation AND converts spaces to dashes?
And example of what I want to change:
Where to? = where-to
Destination(s) = destinations
Travel dates?: = travel-dates
EDIT: I have updated the missing / from the first regex replace. I am finding that Destination(s) is becoming destinations) which is peculiar.
Codepen: http://codepen.io/anon/pen/mAdXJm?editors=0011
You may use the following regex to only match ASCII punctuation and some symbols (source) - maybe we should remove _ from it:
var punct = /[!"#$%&'()*+,.\/:;<=>?#\[\\\]^`{|}~-]+/g;
or a more contracted one since some of these symbols appear in the ASCII table as consecutive chars:
var punct = /[!-\/:-#\[-^`{-~]+/g;
You may chain 2 regex replacements.
var punct = /[!"#$%&'()*+,.\/:;<=>?#\[\\\]^`{|}~-]+/g;
var s = "Where to?"; // = where-to
console.log(s.replace(punct, '').replace(/\s+/, '-').toLowerCase());
s = "Destination(s)"; // = destinations
console.log(s.replace(punct, '').replace(/\s+/, '-').toLowerCase());
console.log(s.replace(punct, '').replace(/\s+/, '-').toLowerCase());
Or use an anonymous method inside the replace with arrow functions (less compatibility, but succint):
var s="Travel dates?:"; // = travel-dates
var o=/([!-\/:-#\[-^`{-~]+)|\s+/g;
console.log(s.replace(o,(m,g)=>g?'':'-').toLowerCase());
Note you may also use XRegExp to match any Unicode punctuation with \pP construct.
Wiktor touched on the subject, but my first thought was an anonymous function using the regex /(\s+)|([\W])/g like this:
var inputs = ['Where to?', 'Destination(s)', 'Travel dates?:'],
res,
idx;
for( idx=0; idx<inputs.length; idx++ ) {
res = inputs[idx].replace(/(\s+)|([\W])/g, function(a, b) {return b ? '-' : '';}).toLowerCase();
document.getElementById('output').innerHTML += '"' + inputs[idx] + '" -> "'
+ res + '"<br/>';
}
<!DOCTYPE html>
<html>
<body>
<p id='output'></p>
</body>
</html>
The regex captures either white space (1+) or a non-word characters. If the first is true the anonymous function returns -, otherwise an empty string.
I need to remove all JavaScript comments from a JavaScript source using the JavaScript RegExp object.
What I need is the pattern for the RegExp.
So far, I've found this:
compressed = compressed.replace(/\/\*.+?\*\/|\/\/.*(?=[\n\r])/g, '');
This pattern works OK for:
/* I'm a comment */
or for:
/*
* I'm a comment aswell
*/
But doesn't seem to work for the inline:
// I'm an inline comment
I'm not quite an expert for RegEx and it's patterns, so I need help.
Also, I' would like to have a RegEx pattern which would remove all those HTML-like comments.
<!-- HTML Comment //--> or <!-- HTML Comment -->
And also those conditional HTML comments, which can be found in various JavaScript sources.
Thanks.
NOTE: Regex is not a lexer or a parser. If you have some weird edge case where you need some oddly nested comments parsed out of a string, use a parser. For the other 98% of the time this regex should work.
I had pretty complex block comments going on with nested asterisks, slashes, etc. The regular expression at the following site worked like a charm:
http://upshots.org/javascript/javascript-regexp-to-remove-comments
(see below for original)
Some modifications have been made, but the integrity of the original regex has been preserved. In order to allow certain double-slash (//) sequences (such as URLs), you must use back reference $1 in your replacement value instead of an empty string. Here it is:
/\/\*[\s\S]*?\*\/|([^\\:]|^)\/\/.*$/gm
// JavaScript:
// source_string.replace(/\/\*[\s\S]*?\*\/|([^\\:]|^)\/\/.*$/gm, '$1');
// PHP:
// preg_replace("/\/\*[\s\S]*?\*\/|([^\\:]|^)\/\/.*$/m", "$1", $source_string);
DEMO: https://regex101.com/r/B8WkuX/1
FAILING USE CASES: There are a few edge cases where this regex fails. An ongoing list of those cases is documented in this public gist. Please update the gist if you can find other cases.
...and if you also want to remove <!-- html comments --> use this:
/\/\*[\s\S]*?\*\/|([^\\:]|^)\/\/.*|<!--[\s\S]*?-->$/
(original - for historical reference only)
// DO NOT USE THIS - SEE ABOVE
/(\/\*([\s\S]*?)\*\/)|(\/\/(.*)$)/gm
try this,
(\/\*[\w\'\s\r\n\*]*\*\/)|(\/\/[\w\s\']*)|(\<![\-\-\s\w\>\/]*\>)
should work :)
I have been putting togethor an expression that needs to do something similar.
the finished product is:
/(?:((["'])(?:(?:\\\\)|\\\2|(?!\\\2)\\|(?!\2).|[\n\r])*\2)|(\/\*(?:(?!\*\/).|[\n\r])*\*\/)|(\/\/[^\n\r]*(?:[\n\r]+|$))|((?:=|:)\s*(?:\/(?:(?:(?!\\*\/).)|\\\\|\\\/|[^\\]\[(?:\\\\|\\\]|[^]])+\])+\/))|((?:\/(?:(?:(?!\\*\/).)|\\\\|\\\/|[^\\]\[(?:\\\\|\\\]|[^]])+\])+\/)[gimy]?\.(?:exec|test|match|search|replace|split)\()|(\.(?:exec|test|match|search|replace|split)\((?:\/(?:(?:(?!\\*\/).)|\\\\|\\\/|[^\\]\[(?:\\\\|\\\]|[^]])+\])+\/))|(<!--(?:(?!-->).)*-->))/g
Scary right?
To break it down, the first part matches anything within single or double quotation marks
This is necessary to avoid matching quoted strings
((["'])(?:(?:\\\\)|\\\2|(?!\\\2)\\|(?!\2).|[\n\r])*\2)
the second part matches multiline comments delimited by /* */
(\/\*(?:(?!\*\/).|[\n\r])*\*\/)
The third part matches single line comments starting anywhere in the line
(\/\/[^\n\r]*(?:[\n\r]+|$))
The fourth through sixth parts matchs anything within a regex literal
This relies on a preceding equals sign or the literal being before or after a regex call
((?:=|:)\s*(?:\/(?:(?:(?!\\*\/).)|\\\\|\\\/|[^\\]\[(?:\\\\|\\\]|[^]])+\])+\/))
((?:\/(?:(?:(?!\\*\/).)|\\\\|\\\/|[^\\]\[(?:\\\\|\\\]|[^]])+\])+\/)[gimy]?\.(?:exec|test|match|search|replace|split)\()
(\.(?:exec|test|match|search|replace|split)\((?:\/(?:(?:(?!\\*\/).)|\\\\|\\\/|[^\\]\[(?:\\\\|\\\]|[^]])+\])+\/))
and the seventh which I originally forgot removes the html comments
(<!--(?:(?!-->).)*-->)
I had an issue with my dev environment issuing errors for a regex that broke a line, so I used the following solution
var ADW_GLOBALS = new Object
ADW_GLOBALS = {
quotations : /((["'])(?:(?:\\\\)|\\\2|(?!\\\2)\\|(?!\2).|[\n\r])*\2)/,
multiline_comment : /(\/\*(?:(?!\*\/).|[\n\r])*\*\/)/,
single_line_comment : /(\/\/[^\n\r]*[\n\r]+)/,
regex_literal : /(?:\/(?:(?:(?!\\*\/).)|\\\\|\\\/|[^\\]\[(?:\\\\|\\\]|[^]])+\])+\/)/,
html_comments : /(<!--(?:(?!-->).)*-->)/,
regex_of_doom : ''
}
ADW_GLOBALS.regex_of_doom = new RegExp(
'(?:' + ADW_GLOBALS.quotations.source + '|' +
ADW_GLOBALS.multiline_comment.source + '|' +
ADW_GLOBALS.single_line_comment.source + '|' +
'((?:=|:)\\s*' + ADW_GLOBALS.regex_literal.source + ')|(' +
ADW_GLOBALS.regex_literal.source + '[gimy]?\\.(?:exec|test|match|search|replace|split)\\(' + ')|(' +
'\\.(?:exec|test|match|search|replace|split)\\(' + ADW_GLOBALS.regex_literal.source + ')|' +
ADW_GLOBALS.html_comments.source + ')' , 'g'
);
changed_text = code_to_test.replace(ADW_GLOBALS.regex_of_doom, function(match, $1, $2, $3, $4, $5, $6, $7, $8, offset, original){
if (typeof $1 != 'undefined') return $1;
if (typeof $5 != 'undefined') return $5;
if (typeof $6 != 'undefined') return $6;
if (typeof $7 != 'undefined') return $7;
return '';
}
This returns anything captured by the quoted string text and anything found in a regex literal intact but returns an empty string for all the comment captures.
I know this is excessive and rather difficult to maintain but it does appear to work for me so far.
This works for almost all cases:
var RE_BLOCKS = new RegExp([
/\/(\*)[^*]*\*+(?:[^*\/][^*]*\*+)*\//.source, // $1: multi-line comment
/\/(\/)[^\n]*$/.source, // $2 single-line comment
/"(?:[^"\\]*|\\[\S\s])*"|'(?:[^'\\]*|\\[\S\s])*'/.source, // - string, don't care about embedded eols
/(?:[$\w\)\]]|\+\+|--)\s*\/(?![*\/])/.source, // - division operator
/\/(?=[^*\/])[^[/\\]*(?:(?:\[(?:\\.|[^\]\\]*)*\]|\\.)[^[/\\]*)*?\/[gim]*/.source
].join('|'), // - regex
'gm' // note: global+multiline with replace() need test
);
// remove comments, keep other blocks
function stripComments(str) {
return str.replace(RE_BLOCKS, function (match, mlc, slc) {
return mlc ? ' ' : // multiline comment (replace with space)
slc ? '' : // single/multiline comment
match; // divisor, regex, or string, return as-is
});
}
The code is based on regexes from jspreproc, I wrote this tool for the riot compiler.
See http://github.com/aMarCruz/jspreproc
In plain simple JS regex, this:
my_string_or_obj.replace(/\/\*[\s\S]*?\*\/|([^:]|^)\/\/.*$/gm, ' ')
a bit simpler -
this works also for multiline - (<!--.*?-->)|(<!--[\w\W\n\s]+?-->)
Simple regex ONLY for multi-lines:
/\*((.|\n)(?!/))+\*/
The accepted solution does not capture all common use cases. See examples here: https://regex101.com/r/38dIQk/1.
The following regular expression should match JavaScript comments more reliably:
/(?:\/\*(?:[^\*]|\**[^\*\/])*\*+\/)|(?:\/\/[\S ]*)/g
For demonstration, visit the following link: https://regex101.com/r/z99Nq5/1/.
This is late to be of much use to the original question, but maybe it will help someone.
Based on #Ryan Wheale's answer, I've found this to work as a comprehensive capture to ensure that matches exclude anything found inside a string literal.
/(?:\r\n|\n|^)(?:[^'"])*?(?:'(?:[^\r\n\\']|\\'|[\\]{2})*'|"(?:[^\r\n\\"]|\\"|[\\]{2})*")*?(?:[^'"])*?(\/\*(?:[\s\S]*?)\*\/|\/\/.*)/g
The last group (all others are discarded) is based on Ryan's answer. Example here.
This assumes code is well structured and valid javascript.
Note: this has not been tested on poorly structured code which may or may not be recoverable depending on the javascript engine's own heuristics.
Note: this should hold for valid javascript < ES6, however, ES6 allows multi-line string literals, in which case this regex will almost certainly break, though that case has not been tested.
However, it is still possible to match something that looks like a comment inside a regex literal (see comments/results in the Example above).
I use the above capture after replacing all regex literals using the following comprehensive capture extracted from es5-lexer here and here, as referenced in Mike Samuel's answer to this question:
/(?:(?:break|case|continue|delete|do|else|finally|in|instanceof|return|throw|try|typeof|void|[+]|-|[.]|[/]|,|[*])|[!%&(:;<=>?[^{|}~])?(\/(?![*/])(?:[^\\\[/\r\n\u2028\u2029]|\[(?:[^\]\\\r\n\u2028\u2029]|\\(?:[^\r\n\u2028\u2029ux]|u[0-9A-Fa-f]{4}|x[0-9A-Fa-f]{2}))+\]|\\(?:[^\r\n\u2028\u2029ux]|u[0-9A-Fa-f]{4}|x[0-9A-Fa-f]{2}))*\/[gim]*)/g
For completeness, see also this trivial caveat.
If you click on the link below you find a comment removal script written in regex.
These are 112 lines off code that work together also works with mootools and Joomla and drupal and other cms websites.
Tested it on 800.000 lines of code and comments. works fine.
This one also selects multiple parenthetical like ( abc(/nn/('/xvx/'))"// testing line") and comments that are between colons and protect them.
23-01-2016..! This is the code with the comments in it.!!!!
Click Here
I was looking for a quick Regex solution too, but none of the answers provided work 100%. Each one ends up breaking the source code in some way, mostly due to comments detected inside string literals. E.g.
var string = "https://www.google.com/";
Becomes
var string = "https:
For the benefit of those coming in from google, I ended up writing a short function (in Javascript) that achieves what the Regex couldn't do. Modify for whatever language you are using to parse Javascript.
function removeCodeComments(code) {
var inQuoteChar = null;
var inBlockComment = false;
var inLineComment = false;
var inRegexLiteral = false;
var newCode = '';
for (var i=0; i<code.length; i++) {
if (!inQuoteChar && !inBlockComment && !inLineComment && !inRegexLiteral) {
if (code[i] === '"' || code[i] === "'" || code[i] === '`') {
inQuoteChar = code[i];
}
else if (code[i] === '/' && code[i+1] === '*') {
inBlockComment = true;
}
else if (code[i] === '/' && code[i+1] === '/') {
inLineComment = true;
}
else if (code[i] === '/' && code[i+1] !== '/') {
inRegexLiteral = true;
}
}
else {
if (inQuoteChar && ((code[i] === inQuoteChar && code[i-1] != '\\') || (code[i] === '\n' && inQuoteChar !== '`'))) {
inQuoteChar = null;
}
if (inRegexLiteral && ((code[i] === '/' && code[i-1] !== '\\') || code[i] === '\n')) {
inRegexLiteral = false;
}
if (inBlockComment && code[i-1] === '/' && code[i-2] === '*') {
inBlockComment = false;
}
if (inLineComment && code[i] === '\n') {
inLineComment = false;
}
}
if (!inBlockComment && !inLineComment) {
newCode += code[i];
}
}
return newCode;
}
2019:
All other answers are incomplete and full of shortcomings. I take the time to write complete answer that WORK
function stripComments(code){
const savedText = [];
return code
.replace(/(['"`]).*?\1/gm,function (match) {
var i = savedText.push(match);
return (i-1)+'###';
})
// remove // comments
.replace(/\/\/.*/gm,'')
// now extract all regex and save them
.replace(/\/[^*\n].*\//gm,function (match) {
var i = savedText.push(match);
return (i-1)+'###';
})
// remove /* */ comments
.replace(/\/\*[\s\S]*\*\//gm,'')
// remove <!-- --> comments
.replace(/<!--[\s\S]*-->/gm, '')
.replace(/\d+###/gm,function(match){
var i = Number.parseInt(match);
return savedText[i];
})
}
var cleancode = stripComments(stripComments.toString())
console.log(cleancode)
Other answers not working on samples code like that:
// won't execute the creative code ("Can't execute code form a freed script"),
navigator.userAgent.match(/\b(MSIE |Trident.*?rv:|Edge\/)(\d+)/);
function stripComments(code){
const savedText = [];
return code
// extract strings and regex
.replace(/(['"`]).*?\1/gm,function (match) {
savedText.push(match);
return '###';
})
// remove // comments
.replace(/\/\/.*/gm,'')
// now extract all regex and save them
.replace(/\/[^*\n].*\//gm,function (match) {
savedText.push(match);
return '###';
})
// remove /* */ comments
.replace(/\/\*[\s\S]*\*\//gm,'')
// remove <!-- --> comments
.replace(/<!--[\s\S]*-->/gm, '')
/*replace \ with \\ so we not lost \b && \t*/
.replace(/###/gm,function(){
return savedText.shift();
})
}
var cleancode = stripComments(stripComments.toString())
console.log(cleancode)
for /**/ and //
/(?:(?:\/\*(?:[^*]|(?:\*+[^*\/]))*\*+\/)|(?:(?<!\:|\\\|\')\/\/.*))/gm
I wonder if this was a trick question given by
a professor to students. Why? Because it seems
to me it is IMPOSSIBLE to do this, with
Regular Expressions, in the general case.
Your (or whoever's code it is) can contain
valid JavaScript like this:
let a = "hello /* ";
let b = 123;
let c = "world */ ";
Now if you have a regexp which removes everything
between a pair of /* and */, it would break the code
above, it would remove the executable code in the
middle as well.
If you try to devise a regexp that would not
remove comments which contain quotes then
you cannot remove such comments. That applies
to single-quote, double-quotes and back-quotes.
You can not remove (all) comments with Regular
Expressions in JavaScript, it seems to me,
maybe someone can point out a way how to do
it for the case above.
What you can do is build a small parser which
goes through the code character by character
and knows when it is inside a string and when
it is inside a comment, and when it is inside
a comment inside a string and so on.
I'm sure there are good open source JavaScript
parsers that can do this. Maybe some of the
packaging and minifying tools can do this for
you as well.
For block comment:
https://regex101.com/r/aepSSj/1
Matches slash character (the \1) only if slash character is followed by asterisk.
(\/)(?=\*)
maybe followed by another asterisk
(?:\*)
followed by first group of match, or zero or more times from something...maybe, without remember the match but capture as a group.
((?:\1|[\s\S])*?)
followed by asterisk and first group
(?:\*)\1
For block and/or inline comment:
https://regex101.com/r/aepSSj/2
where | mean or and (?=\/\/(.*)) capture anything after any //
or https://regex101.com/r/aepSSj/3
to capture the third part too
all in: https://regex101.com/r/aepSSj/8
DEMO: https://onecompiler.com/javascript/3y825u3d5
const context = `
<html>
<script type="module">
/* I'm a comment */
/*
* I'm a comment aswell url="https://example.com/";
*/
var re = /\\/*not a comment!*/;
var m = /\\//.test("\"not a comment!\"");
var re = /"/; // " thiscommentishandledasascode!
const s1 = "multi String \\
\\"double quote\\" \\
// single commet in str \\
/* multiple lines commet in str \\
secend line */ \\
last line";
const s2 = 's2"s';
const url = "https://example.com/questions/5989315/";
let a = "hello /* ";
let b = 123;
let c = "world */ ";
//public static final String LETTERS_WORK_FOLDER = "/Letters/Generated/Work";
console.log(/*comment in
console.log*/ "!message at console.log");
function displayMsg( // the end comment
/*commet arg1*/ a, ...args) {
console.log("Hello World!", a, ...args)
}
<\/script>
<body>
<!-- HTML Comment //--> or <!-- HTML Comment -->
<!--
function displayMsg() {
alert("Hello World!")
}
//-->
</body>
</html>
`;
console.log("before:\n" + context);
console.log("<".repeat(100));
const save = {'txt':[], 'comment':[], 'regex': []};
const context2 =
context.replace(/(['"`]|\/[\*\/]{0,1}|<!\-\-)(?:(?=(?<=\/\*))[\s\S]*?\*\/|(?=(?<=\/\/)).*|(?=(?<=<!\-\-))[\s\S]*?\-\->|(?=(?<=[\s\=]\/)).+?(?<!\\)\/|(?=(?<=['"`]))[\s\S]*?(?<!\\)\1)/g,
function (m) {
const t = (m[0].match(/["'`]/) && 'txt') || (m.match(/^(\/\/|\/\*|<)/) && 'comment') || 'regex';
save[t].push(m);
return '${save.'+t+'['+(save[t].length - 1)+']}';
}).replace(/[\S\s]*/, function(m) {
console.log("watch:\n"+m);
console.log(">".repeat(100));
/*
##remove comment
save.comment = save.comment.map(_ => _.replace(/[\S\s]+/,""));
##replace comment
save.comment = save.comment.map(_ => _.replace(/console\.log/g, 'CONSOLE.LOG'));
##replace text
save.txt = save.txt.map(_ => _.replace(/console\.log/g, 'CONSOLE.LOG'));
##replace your code
m = m.replace(/console\.log/g, 'console.warn');
*/
// console.warn("##remove comment -> save.comment.fill('');");
save.comment.fill('');
return m;
}).replace(/\$\{save.(\w+)\[(\d+)\]\}/g, function(m, t, id) {
return save[t][id];
}).replace(/[\S\s]*/, function(m) {
console.log("result:", m);
// console.log("compare:", (context === m));
return m;
})
My English is not good, can someone help translate what I have written, I will be very grateful
Consider some problems
A.There may be strings in comments, or comments in strings, like
/*
const url="https://example.com/";
*/
const str = "i am s string and /*commet in string*/";
B. " or ' or ` in a string will be escaped with
like
const str = "my name is \"john\"";
const str2 = 'i am "john\'s" friend';
Combining the above multiple regex replaces will cause some problems
Consider regex find to the beginning part
" ' ` // /* <!--
use regex
(['"`]|\/[\*\/]|<!\-\-)
(['"`]|/[*/]|<!\-\-) result as \1
\1 is one of ' or " or
`
or /* or // or <!--
use If-Then-Else Conditionals in Regular Expressions
https://www.regular-expressions.info/conditional.html
(?:(?=(?<=\/\*))[\s\S]*?\*\/|(?=(?<=\/\/)).*|(?=(?<=<!\-\-))[\s\S]*?\-\->|[^\1]*?(?<!\\)\1)
if (?=(?<=\/\*))[\s\S]*?\*\/
(?=(?<=\/\*)) positive lookbehind (?<=\/\*) beacuse/*
It's a multi-line comment, so it should be followed by the latest one */
[\s\S]*?\*\/ match complete /*..\n..\n. */
elseif (?=(?<=\/\/)).*
(?=(?<=//)).* positive lookbehind
(?<=\/\/) catch // single line commet
.* match complete // any single commet
elseif (?=(?<=<!\-\-))[\s\S]*?\-\->
(?=(?<=<!--)) positive lookbehind (?<=<!\-\-) ，
[\s\S]*?\-\-> match complete
<!--..\n..\n. /*/*\-\->
else [^\1]*?(?<!\\)\1
Finally need to process the string
use regex [\s\S]*?\1
maybe the wrong result with "STR\" or 'STR"S\'
at [\s\S]*?we can use "positive lookbehind"
add this [\s\S]*?(?<!\\)\1 to filter escape quotes
end
Based on above attempts and using UltraEdit , mostly Abhishek Simon, I found this to work for inline comments and handles all of the characters within the comment.
(\s\/\/|$\/\/)[\w\s\W\S.]*
This matches comments at the start of the line or with a space before //
//public static final String LETTERS_WORK_FOLDER =
"/Letters/Generated/Work";
but not
"http://schemas.us.com.au/hub/'>" +
so it is only not good for something like
if(x){f(x)}//where f is some function
it just needs to be
if(x){f(x)} //where f is function
I need to remove all JavaScript comments from a JavaScript source using the JavaScript RegExp object.
What I need is the pattern for the RegExp.
So far, I've found this:
compressed = compressed.replace(/\/\*.+?\*\/|\/\/.*(?=[\n\r])/g, '');
This pattern works OK for:
/* I'm a comment */
or for:
/*
* I'm a comment aswell
*/
But doesn't seem to work for the inline:
// I'm an inline comment
I'm not quite an expert for RegEx and it's patterns, so I need help.
Also, I' would like to have a RegEx pattern which would remove all those HTML-like comments.
<!-- HTML Comment //--> or <!-- HTML Comment -->
And also those conditional HTML comments, which can be found in various JavaScript sources.
Thanks.
NOTE: Regex is not a lexer or a parser. If you have some weird edge case where you need some oddly nested comments parsed out of a string, use a parser. For the other 98% of the time this regex should work.
I had pretty complex block comments going on with nested asterisks, slashes, etc. The regular expression at the following site worked like a charm:
http://upshots.org/javascript/javascript-regexp-to-remove-comments
(see below for original)
Some modifications have been made, but the integrity of the original regex has been preserved. In order to allow certain double-slash (//) sequences (such as URLs), you must use back reference $1 in your replacement value instead of an empty string. Here it is:
/\/\*[\s\S]*?\*\/|([^\\:]|^)\/\/.*$/gm
// JavaScript:
// source_string.replace(/\/\*[\s\S]*?\*\/|([^\\:]|^)\/\/.*$/gm, '$1');
// PHP:
// preg_replace("/\/\*[\s\S]*?\*\/|([^\\:]|^)\/\/.*$/m", "$1", $source_string);
DEMO: https://regex101.com/r/B8WkuX/1
FAILING USE CASES: There are a few edge cases where this regex fails. An ongoing list of those cases is documented in this public gist. Please update the gist if you can find other cases.
...and if you also want to remove <!-- html comments --> use this:
/\/\*[\s\S]*?\*\/|([^\\:]|^)\/\/.*|<!--[\s\S]*?-->$/
(original - for historical reference only)
// DO NOT USE THIS - SEE ABOVE
/(\/\*([\s\S]*?)\*\/)|(\/\/(.*)$)/gm
try this,
(\/\*[\w\'\s\r\n\*]*\*\/)|(\/\/[\w\s\']*)|(\<![\-\-\s\w\>\/]*\>)
should work :)
I have been putting togethor an expression that needs to do something similar.
the finished product is:
/(?:((["'])(?:(?:\\\\)|\\\2|(?!\\\2)\\|(?!\2).|[\n\r])*\2)|(\/\*(?:(?!\*\/).|[\n\r])*\*\/)|(\/\/[^\n\r]*(?:[\n\r]+|$))|((?:=|:)\s*(?:\/(?:(?:(?!\\*\/).)|\\\\|\\\/|[^\\]\[(?:\\\\|\\\]|[^]])+\])+\/))|((?:\/(?:(?:(?!\\*\/).)|\\\\|\\\/|[^\\]\[(?:\\\\|\\\]|[^]])+\])+\/)[gimy]?\.(?:exec|test|match|search|replace|split)\()|(\.(?:exec|test|match|search|replace|split)\((?:\/(?:(?:(?!\\*\/).)|\\\\|\\\/|[^\\]\[(?:\\\\|\\\]|[^]])+\])+\/))|(<!--(?:(?!-->).)*-->))/g
Scary right?
To break it down, the first part matches anything within single or double quotation marks
This is necessary to avoid matching quoted strings
((["'])(?:(?:\\\\)|\\\2|(?!\\\2)\\|(?!\2).|[\n\r])*\2)
the second part matches multiline comments delimited by /* */
(\/\*(?:(?!\*\/).|[\n\r])*\*\/)
The third part matches single line comments starting anywhere in the line
(\/\/[^\n\r]*(?:[\n\r]+|$))
The fourth through sixth parts matchs anything within a regex literal
This relies on a preceding equals sign or the literal being before or after a regex call
((?:=|:)\s*(?:\/(?:(?:(?!\\*\/).)|\\\\|\\\/|[^\\]\[(?:\\\\|\\\]|[^]])+\])+\/))
((?:\/(?:(?:(?!\\*\/).)|\\\\|\\\/|[^\\]\[(?:\\\\|\\\]|[^]])+\])+\/)[gimy]?\.(?:exec|test|match|search|replace|split)\()
(\.(?:exec|test|match|search|replace|split)\((?:\/(?:(?:(?!\\*\/).)|\\\\|\\\/|[^\\]\[(?:\\\\|\\\]|[^]])+\])+\/))
and the seventh which I originally forgot removes the html comments
(<!--(?:(?!-->).)*-->)
I had an issue with my dev environment issuing errors for a regex that broke a line, so I used the following solution
var ADW_GLOBALS = new Object
ADW_GLOBALS = {
quotations : /((["'])(?:(?:\\\\)|\\\2|(?!\\\2)\\|(?!\2).|[\n\r])*\2)/,
multiline_comment : /(\/\*(?:(?!\*\/).|[\n\r])*\*\/)/,
single_line_comment : /(\/\/[^\n\r]*[\n\r]+)/,
regex_literal : /(?:\/(?:(?:(?!\\*\/).)|\\\\|\\\/|[^\\]\[(?:\\\\|\\\]|[^]])+\])+\/)/,
html_comments : /(<!--(?:(?!-->).)*-->)/,
regex_of_doom : ''
}
ADW_GLOBALS.regex_of_doom = new RegExp(
'(?:' + ADW_GLOBALS.quotations.source + '|' +
ADW_GLOBALS.multiline_comment.source + '|' +
ADW_GLOBALS.single_line_comment.source + '|' +
'((?:=|:)\\s*' + ADW_GLOBALS.regex_literal.source + ')|(' +
ADW_GLOBALS.regex_literal.source + '[gimy]?\\.(?:exec|test|match|search|replace|split)\\(' + ')|(' +
'\\.(?:exec|test|match|search|replace|split)\\(' + ADW_GLOBALS.regex_literal.source + ')|' +
ADW_GLOBALS.html_comments.source + ')' , 'g'
);
changed_text = code_to_test.replace(ADW_GLOBALS.regex_of_doom, function(match, $1, $2, $3, $4, $5, $6, $7, $8, offset, original){
if (typeof $1 != 'undefined') return $1;
if (typeof $5 != 'undefined') return $5;
if (typeof $6 != 'undefined') return $6;
if (typeof $7 != 'undefined') return $7;
return '';
}
This returns anything captured by the quoted string text and anything found in a regex literal intact but returns an empty string for all the comment captures.
I know this is excessive and rather difficult to maintain but it does appear to work for me so far.
This works for almost all cases:
var RE_BLOCKS = new RegExp([
/\/(\*)[^*]*\*+(?:[^*\/][^*]*\*+)*\//.source, // $1: multi-line comment
/\/(\/)[^\n]*$/.source, // $2 single-line comment
/"(?:[^"\\]*|\\[\S\s])*"|'(?:[^'\\]*|\\[\S\s])*'/.source, // - string, don't care about embedded eols
/(?:[$\w\)\]]|\+\+|--)\s*\/(?![*\/])/.source, // - division operator
/\/(?=[^*\/])[^[/\\]*(?:(?:\[(?:\\.|[^\]\\]*)*\]|\\.)[^[/\\]*)*?\/[gim]*/.source
].join('|'), // - regex
'gm' // note: global+multiline with replace() need test
);
// remove comments, keep other blocks
function stripComments(str) {
return str.replace(RE_BLOCKS, function (match, mlc, slc) {
return mlc ? ' ' : // multiline comment (replace with space)
slc ? '' : // single/multiline comment
match; // divisor, regex, or string, return as-is
});
}
The code is based on regexes from jspreproc, I wrote this tool for the riot compiler.
See http://github.com/aMarCruz/jspreproc
In plain simple JS regex, this:
my_string_or_obj.replace(/\/\*[\s\S]*?\*\/|([^:]|^)\/\/.*$/gm, ' ')
a bit simpler -
this works also for multiline - (<!--.*?-->)|(<!--[\w\W\n\s]+?-->)
Simple regex ONLY for multi-lines:
/\*((.|\n)(?!/))+\*/
The accepted solution does not capture all common use cases. See examples here: https://regex101.com/r/38dIQk/1.
The following regular expression should match JavaScript comments more reliably:
/(?:\/\*(?:[^\*]|\**[^\*\/])*\*+\/)|(?:\/\/[\S ]*)/g
For demonstration, visit the following link: https://regex101.com/r/z99Nq5/1/.
This is late to be of much use to the original question, but maybe it will help someone.
Based on #Ryan Wheale's answer, I've found this to work as a comprehensive capture to ensure that matches exclude anything found inside a string literal.
/(?:\r\n|\n|^)(?:[^'"])*?(?:'(?:[^\r\n\\']|\\'|[\\]{2})*'|"(?:[^\r\n\\"]|\\"|[\\]{2})*")*?(?:[^'"])*?(\/\*(?:[\s\S]*?)\*\/|\/\/.*)/g
The last group (all others are discarded) is based on Ryan's answer. Example here.
This assumes code is well structured and valid javascript.
Note: this has not been tested on poorly structured code which may or may not be recoverable depending on the javascript engine's own heuristics.
Note: this should hold for valid javascript < ES6, however, ES6 allows multi-line string literals, in which case this regex will almost certainly break, though that case has not been tested.
However, it is still possible to match something that looks like a comment inside a regex literal (see comments/results in the Example above).
I use the above capture after replacing all regex literals using the following comprehensive capture extracted from es5-lexer here and here, as referenced in Mike Samuel's answer to this question:
/(?:(?:break|case|continue|delete|do|else|finally|in|instanceof|return|throw|try|typeof|void|[+]|-|[.]|[/]|,|[*])|[!%&(:;<=>?[^{|}~])?(\/(?![*/])(?:[^\\\[/\r\n\u2028\u2029]|\[(?:[^\]\\\r\n\u2028\u2029]|\\(?:[^\r\n\u2028\u2029ux]|u[0-9A-Fa-f]{4}|x[0-9A-Fa-f]{2}))+\]|\\(?:[^\r\n\u2028\u2029ux]|u[0-9A-Fa-f]{4}|x[0-9A-Fa-f]{2}))*\/[gim]*)/g
For completeness, see also this trivial caveat.
If you click on the link below you find a comment removal script written in regex.
These are 112 lines off code that work together also works with mootools and Joomla and drupal and other cms websites.
Tested it on 800.000 lines of code and comments. works fine.
This one also selects multiple parenthetical like ( abc(/nn/('/xvx/'))"// testing line") and comments that are between colons and protect them.
23-01-2016..! This is the code with the comments in it.!!!!
Click Here
I was looking for a quick Regex solution too, but none of the answers provided work 100%. Each one ends up breaking the source code in some way, mostly due to comments detected inside string literals. E.g.
var string = "https://www.google.com/";
Becomes
var string = "https:
For the benefit of those coming in from google, I ended up writing a short function (in Javascript) that achieves what the Regex couldn't do. Modify for whatever language you are using to parse Javascript.
function removeCodeComments(code) {
var inQuoteChar = null;
var inBlockComment = false;
var inLineComment = false;
var inRegexLiteral = false;
var newCode = '';
for (var i=0; i<code.length; i++) {
if (!inQuoteChar && !inBlockComment && !inLineComment && !inRegexLiteral) {
if (code[i] === '"' || code[i] === "'" || code[i] === '`') {
inQuoteChar = code[i];
}
else if (code[i] === '/' && code[i+1] === '*') {
inBlockComment = true;
}
else if (code[i] === '/' && code[i+1] === '/') {
inLineComment = true;
}
else if (code[i] === '/' && code[i+1] !== '/') {
inRegexLiteral = true;
}
}
else {
if (inQuoteChar && ((code[i] === inQuoteChar && code[i-1] != '\\') || (code[i] === '\n' && inQuoteChar !== '`'))) {
inQuoteChar = null;
}
if (inRegexLiteral && ((code[i] === '/' && code[i-1] !== '\\') || code[i] === '\n')) {
inRegexLiteral = false;
}
if (inBlockComment && code[i-1] === '/' && code[i-2] === '*') {
inBlockComment = false;
}
if (inLineComment && code[i] === '\n') {
inLineComment = false;
}
}
if (!inBlockComment && !inLineComment) {
newCode += code[i];
}
}
return newCode;
}
2019:
All other answers are incomplete and full of shortcomings. I take the time to write complete answer that WORK
function stripComments(code){
const savedText = [];
return code
.replace(/(['"`]).*?\1/gm,function (match) {
var i = savedText.push(match);
return (i-1)+'###';
})
// remove // comments
.replace(/\/\/.*/gm,'')
// now extract all regex and save them
.replace(/\/[^*\n].*\//gm,function (match) {
var i = savedText.push(match);
return (i-1)+'###';
})
// remove /* */ comments
.replace(/\/\*[\s\S]*\*\//gm,'')
// remove <!-- --> comments
.replace(/<!--[\s\S]*-->/gm, '')
.replace(/\d+###/gm,function(match){
var i = Number.parseInt(match);
return savedText[i];
})
}
var cleancode = stripComments(stripComments.toString())
console.log(cleancode)
Other answers not working on samples code like that:
// won't execute the creative code ("Can't execute code form a freed script"),
navigator.userAgent.match(/\b(MSIE |Trident.*?rv:|Edge\/)(\d+)/);
function stripComments(code){
const savedText = [];
return code
// extract strings and regex
.replace(/(['"`]).*?\1/gm,function (match) {
savedText.push(match);
return '###';
})
// remove // comments
.replace(/\/\/.*/gm,'')
// now extract all regex and save them
.replace(/\/[^*\n].*\//gm,function (match) {
savedText.push(match);
return '###';
})
// remove /* */ comments
.replace(/\/\*[\s\S]*\*\//gm,'')
// remove <!-- --> comments
.replace(/<!--[\s\S]*-->/gm, '')
/*replace \ with \\ so we not lost \b && \t*/
.replace(/###/gm,function(){
return savedText.shift();
})
}
var cleancode = stripComments(stripComments.toString())
console.log(cleancode)
for /**/ and //
/(?:(?:\/\*(?:[^*]|(?:\*+[^*\/]))*\*+\/)|(?:(?<!\:|\\\|\')\/\/.*))/gm
I wonder if this was a trick question given by
a professor to students. Why? Because it seems
to me it is IMPOSSIBLE to do this, with
Regular Expressions, in the general case.
Your (or whoever's code it is) can contain
valid JavaScript like this:
let a = "hello /* ";
let b = 123;
let c = "world */ ";
Now if you have a regexp which removes everything
between a pair of /* and */, it would break the code
above, it would remove the executable code in the
middle as well.
If you try to devise a regexp that would not
remove comments which contain quotes then
you cannot remove such comments. That applies
to single-quote, double-quotes and back-quotes.
You can not remove (all) comments with Regular
Expressions in JavaScript, it seems to me,
maybe someone can point out a way how to do
it for the case above.
What you can do is build a small parser which
goes through the code character by character
and knows when it is inside a string and when
it is inside a comment, and when it is inside
a comment inside a string and so on.
I'm sure there are good open source JavaScript
parsers that can do this. Maybe some of the
packaging and minifying tools can do this for
you as well.
For block comment:
https://regex101.com/r/aepSSj/1
Matches slash character (the \1) only if slash character is followed by asterisk.
(\/)(?=\*)
maybe followed by another asterisk
(?:\*)
followed by first group of match, or zero or more times from something...maybe, without remember the match but capture as a group.
((?:\1|[\s\S])*?)
followed by asterisk and first group
(?:\*)\1
For block and/or inline comment:
https://regex101.com/r/aepSSj/2
where | mean or and (?=\/\/(.*)) capture anything after any //
or https://regex101.com/r/aepSSj/3
to capture the third part too
all in: https://regex101.com/r/aepSSj/8
DEMO: https://onecompiler.com/javascript/3y825u3d5
const context = `
<html>
<script type="module">
/* I'm a comment */
/*
* I'm a comment aswell url="https://example.com/";
*/
var re = /\\/*not a comment!*/;
var m = /\\//.test("\"not a comment!\"");
var re = /"/; // " thiscommentishandledasascode!
const s1 = "multi String \\
\\"double quote\\" \\
// single commet in str \\
/* multiple lines commet in str \\
secend line */ \\
last line";
const s2 = 's2"s';
const url = "https://example.com/questions/5989315/";
let a = "hello /* ";
let b = 123;
let c = "world */ ";
//public static final String LETTERS_WORK_FOLDER = "/Letters/Generated/Work";
console.log(/*comment in
console.log*/ "!message at console.log");
function displayMsg( // the end comment
/*commet arg1*/ a, ...args) {
console.log("Hello World!", a, ...args)
}
<\/script>
<body>
<!-- HTML Comment //--> or <!-- HTML Comment -->
<!--
function displayMsg() {
alert("Hello World!")
}
//-->
</body>
</html>
`;
console.log("before:\n" + context);
console.log("<".repeat(100));
const save = {'txt':[], 'comment':[], 'regex': []};
const context2 =
context.replace(/(['"`]|\/[\*\/]{0,1}|<!\-\-)(?:(?=(?<=\/\*))[\s\S]*?\*\/|(?=(?<=\/\/)).*|(?=(?<=<!\-\-))[\s\S]*?\-\->|(?=(?<=[\s\=]\/)).+?(?<!\\)\/|(?=(?<=['"`]))[\s\S]*?(?<!\\)\1)/g,
function (m) {
const t = (m[0].match(/["'`]/) && 'txt') || (m.match(/^(\/\/|\/\*|<)/) && 'comment') || 'regex';
save[t].push(m);
return '${save.'+t+'['+(save[t].length - 1)+']}';
}).replace(/[\S\s]*/, function(m) {
console.log("watch:\n"+m);
console.log(">".repeat(100));
/*
##remove comment
save.comment = save.comment.map(_ => _.replace(/[\S\s]+/,""));
##replace comment
save.comment = save.comment.map(_ => _.replace(/console\.log/g, 'CONSOLE.LOG'));
##replace text
save.txt = save.txt.map(_ => _.replace(/console\.log/g, 'CONSOLE.LOG'));
##replace your code
m = m.replace(/console\.log/g, 'console.warn');
*/
// console.warn("##remove comment -> save.comment.fill('');");
save.comment.fill('');
return m;
}).replace(/\$\{save.(\w+)\[(\d+)\]\}/g, function(m, t, id) {
return save[t][id];
}).replace(/[\S\s]*/, function(m) {
console.log("result:", m);
// console.log("compare:", (context === m));
return m;
})
My English is not good, can someone help translate what I have written, I will be very grateful
Consider some problems
A.There may be strings in comments, or comments in strings, like
/*
const url="https://example.com/";
*/
const str = "i am s string and /*commet in string*/";
B. " or ' or ` in a string will be escaped with
like
const str = "my name is \"john\"";
const str2 = 'i am "john\'s" friend';
Combining the above multiple regex replaces will cause some problems
Consider regex find to the beginning part
" ' ` // /* <!--
use regex
(['"`]|\/[\*\/]|<!\-\-)
(['"`]|/[*/]|<!\-\-) result as \1
\1 is one of ' or " or
`
or /* or // or <!--
use If-Then-Else Conditionals in Regular Expressions
https://www.regular-expressions.info/conditional.html
(?:(?=(?<=\/\*))[\s\S]*?\*\/|(?=(?<=\/\/)).*|(?=(?<=<!\-\-))[\s\S]*?\-\->|[^\1]*?(?<!\\)\1)
if (?=(?<=\/\*))[\s\S]*?\*\/
(?=(?<=\/\*)) positive lookbehind (?<=\/\*) beacuse/*
It's a multi-line comment, so it should be followed by the latest one */
[\s\S]*?\*\/ match complete /*..\n..\n. */
elseif (?=(?<=\/\/)).*
(?=(?<=//)).* positive lookbehind
(?<=\/\/) catch // single line commet
.* match complete // any single commet
elseif (?=(?<=<!\-\-))[\s\S]*?\-\->
(?=(?<=<!--)) positive lookbehind (?<=<!\-\-) ，
[\s\S]*?\-\-> match complete
<!--..\n..\n. /*/*\-\->
else [^\1]*?(?<!\\)\1
Finally need to process the string
use regex [\s\S]*?\1
maybe the wrong result with "STR\" or 'STR"S\'
at [\s\S]*?we can use "positive lookbehind"
add this [\s\S]*?(?<!\\)\1 to filter escape quotes
end
Based on above attempts and using UltraEdit , mostly Abhishek Simon, I found this to work for inline comments and handles all of the characters within the comment.
(\s\/\/|$\/\/)[\w\s\W\S.]*
This matches comments at the start of the line or with a space before //
//public static final String LETTERS_WORK_FOLDER =
"/Letters/Generated/Work";
but not
"http://schemas.us.com.au/hub/'>" +
so it is only not good for something like
if(x){f(x)}//where f is some function
it just needs to be
if(x){f(x)} //where f is function