So basically, I have a regular expression which is
var regex1 = /10661\" class=\"fauxBlockLink-linkRow u-concealed\">([\s\S]*?)<\/a>/;
var result=text.match(regex1);
user_activity = result[1].replace(/\s/g, "")
console.log(user_activity);
What I'm trying to do is this
var number = 1234;
var regex1 = /${number}\" class=\"fauxBlockLink-linkRow u-concealed\">([\s\S]*?)<\/a>/;
but it is not working, and when I tried with RegExp, I kept getting errors.
You can use RegExp to create regexp from a string and use variables in that string.
var number = 1234;
var regex1 = new RegExp(`${number}aa`);
console.log("1234aa".match(regex1));
You can build the regex string with templates and/or string addition and then pass it to the RegExp constructor. One key in doing that is to get the escaping correct as you need an extra level of escaping for backslashes because the interpretation of the string takes one level of backslash, but you need one to survive as it gets to the RegExp contructor. Here's a working example:
function match(number, str) {
let r = new RegExp(`${number}" class="fauxBlockLink-linkRow u-concealed">([\\s\\S]*?)<\\/a>`);
return str.match(r);
}
const exampleHTML = 'Some link text';
console.log(match(1234, exampleHTML));
Note, using regex to match HTML like this becomes very order-sensitive (whereas the HTML itself isn't order-sensitive). And, your regex requires exactly one space between classes which HTML doesn't. If the class names were in a slightly different order or spacing different in the <a> tag, then it would not match. Depending upon what you're really trying to do, there may be better ways to parse and use the HTML that isn't order-sensitive.
I solved it with the method of Adem,
function escapeRegExp(string) {
return string.replace(/[.*+?^${}()|[\]\\]/g, '\\$&'); // $& means the whole matched string
}
var number = 1234;
var firstPart = `<a href="/forum/search/member?user_id=${number}" class="fauxBlockLink-linkRow u-concealed">`
var regexpString = escapeRegExp(firstPart) + '([\\s\\S]*?)' + escapeRegExp('</a>');
console.log(regexpString)
var sample = ` `
var regex1 = new RegExp(regexpString);
console.log(sample.match(regex1));
in the first place the issue was actually the way I was reading the file, the data I was applying the match on, was undefined.
Related
I am trying to create something similar to this:
var regexp_loc = /e/i;
except I want the regexp to be dependent on a string, so I tried to use new RegExp but I couldn't get what i wanted.
Basically I want the e in the above regexp to be a string variable but I fail with the syntax.
I tried something like this:
var keyword = "something";
var test_regexp = new RegExp("/" + keyword + "/i");
Basically I want to search for a sub string in a larger string then replace the string with some other string, case insensitive.
regards,
alexander
You need to pass the second parameter:
var r = new RegExp(keyword, "i");
You will also need to escape any special characters in the string to prevent regex injection attacks.
You should also remember to watch out for escape characters within a string...
For example if you wished to detect for a single number \d{1} and you did this...
var pattern = "\d{1}";
var re = new RegExp(pattern);
re.exec("1"); // fail! :(
that would fail as the initial \ is an escape character, you would need to "escape the escape", like so...
var pattern = "\\d{1}" // <-- spot the extra '\'
var re = new RegExp(pattern);
re.exec("1"); // success! :D
When using the RegExp constructor, you don't need the slashes like you do when using a regexp literal. So:
new RegExp(keyword, "i");
Note that you pass in the flags in the second parameter. See here for more info.
Want to share an example here:
I want to replace a string like: hi[var1][var2] to hi[newVar][var2].
and var1 are dynamic generated in the page.
so I had to use:
var regex = new RegExp("\\\\["+var1+"\\\\]",'ig');
mystring.replace(regex,'[newVar]');
This works pretty good to me. in case anyone need this like me.
The reason I have to go with [] is var1 might be a very easy pattern itself, adding the [] would be much accurate.
var keyword = "something";
var test_regexp = new RegExp(something,"i");
You need to convert RegExp, you actually can create a simple function to do it for you:
function toReg(str) {
if(!str || typeof str !== "string") {
return;
}
return new RegExp(str, "i");
}
and call it like:
toReg("something")
I am trying to create something similar to this:
var regexp_loc = /e/i;
except I want the regexp to be dependent on a string, so I tried to use new RegExp but I couldn't get what i wanted.
Basically I want the e in the above regexp to be a string variable but I fail with the syntax.
I tried something like this:
var keyword = "something";
var test_regexp = new RegExp("/" + keyword + "/i");
Basically I want to search for a sub string in a larger string then replace the string with some other string, case insensitive.
regards,
alexander
You need to pass the second parameter:
var r = new RegExp(keyword, "i");
You will also need to escape any special characters in the string to prevent regex injection attacks.
You should also remember to watch out for escape characters within a string...
For example if you wished to detect for a single number \d{1} and you did this...
var pattern = "\d{1}";
var re = new RegExp(pattern);
re.exec("1"); // fail! :(
that would fail as the initial \ is an escape character, you would need to "escape the escape", like so...
var pattern = "\\d{1}" // <-- spot the extra '\'
var re = new RegExp(pattern);
re.exec("1"); // success! :D
When using the RegExp constructor, you don't need the slashes like you do when using a regexp literal. So:
new RegExp(keyword, "i");
Note that you pass in the flags in the second parameter. See here for more info.
Want to share an example here:
I want to replace a string like: hi[var1][var2] to hi[newVar][var2].
and var1 are dynamic generated in the page.
so I had to use:
var regex = new RegExp("\\\\["+var1+"\\\\]",'ig');
mystring.replace(regex,'[newVar]');
This works pretty good to me. in case anyone need this like me.
The reason I have to go with [] is var1 might be a very easy pattern itself, adding the [] would be much accurate.
var keyword = "something";
var test_regexp = new RegExp(something,"i");
You need to convert RegExp, you actually can create a simple function to do it for you:
function toReg(str) {
if(!str || typeof str !== "string") {
return;
}
return new RegExp(str, "i");
}
and call it like:
toReg("something")
I'm doing kind of a reverse templating thing, I have a string, and I know the template used to generate it, I want to get the variable value.
For example:
URL: http://c.tile.osm.org/24/7881145/7385476.png
Template: http://{s}.tile.osm.org/{z}/{x}/{y}.png
I would like to get the zoom level ({z}) from the tile's URL, in this case 24. This exact Template url will not always be used (it varies based on what basemap is used, etc.), but I'll always be looking for the {z} value.
It looks like blint may have beat me to it, but essentially what you want to do is generate a regular expression from your template and execute it:
function zFromTemplate(str, template) {
var sr = template.replace("?", "\\?")
.replace(/\{[^z]\}/g, ".*?")
.replace(/\{z\}/g, "(.+)");
var rex = new RegExp(sr),
parts = rex.exec(str);
if(parts) {
return parts[1];
}
return null;
}
And here's a codepen demonstrating it's use. If nothing else it's a little more succinct than the originally accepted answer.
You can capture values using a regex. This thread is similar to your case, and here would be your solution:
var myString = "http://c.tile.osm.org/24/7881145/7385476.png";
var myRegexp = /http:\/\/[A-z]\.tile\.osm\.org\/([0-9]+)\/([0-9]+)\/([0-9]+)\.png/;
var match = myRegexp.exec(myString);
alert(match[1]); // 24
And here's the fiddle: http://jsfiddle.net/2sx4t/
EDIT:
Following to your comment, here's the most flexible code I could quickly provide you: http://jsfiddle.net/2sx4t/4/
var myString = "http://c.tile.osm.org/24/7881145/7385476.png";
var myTemplate = "http://{s}.tile.osm.org/{z}/{y}/{x}.png";
var myString2 = "//tiles.arcgis.com/tiles/c/arcgis/rest/services/TimeZones/MapServer/tile/223774/24/2636";
var myTemplate2 = "//tiles.arcgis.com/tiles/{s}/arcgis/rest/services/TimeZones/MapServer/tile/{x}/{z}/{y}";
var z = extractToken(myTemplate, myString, '{z}');
alert(z); // 24
var z2 = extractToken(myTemplate, myString, '{z}');
alert(z2); // 24
The tricks in this code is the combination of the use of template.indexOf(m) to be able to find the order of your tokens and String.replace() to generate the appropriate RegExp.
Note that I shuffled the order of the tokens in myTemplate2and that it sill works.
Don't expect magic from RegExp, magic is in our brains ;-)
Bonus with map return, independantly of other tokens: http://jsfiddle.net/2sx4t/8/
Well, if you're sure that the {z} parameter is the only 1 or 2 digits element in your URL, you can try with regexp:
var myRegexp = /.*\/([0-9]{1,2})\/.*/;
This would match the last occurrence of any one or two digits enclosed in two slashes (/1/, /24/, ...)
I can't remember the name of it, but I believe you can reference already matched strings within a RegExp object. What I want to do is match all tags within a given string eg
<ul><li>something in the list</li></ul>
the RegExp should be able to match only the same tags, then I will use a recursive function to put all the individual matches in an array. The regex that should work if I can reference the first match would be.
var reg = /(?:<(.*)>(.*)<(?:FIRST_MATCH)\/>)/g;
The matched array should then contain
match[0] = "<ul><li>something in the list</li></ul>";
match[1] = "ul";
match[2] = ""; // no text to match
match[3] = "li";
match[4] = "something in the list";
thanks for any help
It seems like you mean backreference (\1, \2):
var s = '<ul><li>something in the list</li></ul>';
s.match(/<([^>]+)><([^>]+)>(.*?)<\/\2><\/\1>/)
// => ["<ul><li>something in the list</li></ul>",
// "ul",
// "li",
// "something in the list"]
The result is not exactly same with what you want. But point is that the backreference \1, \2 match the string that was matched by earlier group.
It is not possible to parse HTML using regular expressions (if you're interested in the specifics, it is because HTML parsing requires a stronger type of automaton than a finite state automaton which is what a regular expression can express - look up FSA vs FST for more info).
You might be able to get away with some hack for a specific problem, but if you want to reliably parse HTML using Javascript then there are other ways to do this. Search the web for: parse html javascript and you'll get plenty of pointers on how to do this.
I made a dirty workaround. Still needs work thought.
var str = '<div><ul id="list"><li class="something">this is the text</li></ul></div>';
function parseHTMLFromString(str){
var structure = [];
var matches = [];
var reg = /(<(.+)(?:\s([^>]+))*>)(.*)<\/\2>/;
str.replace(reg, function(){
//console.log(arguments);
matches.push(arguments[4]);
structure.push(arguments[1], arguments[4]);
});
while(matches.length){
matches.shift().replace(reg, function(){
console.log(arguments);
structure.pop();
structure.push(arguments[1], arguments[4]);
matches.push(arguments[4]);
});
}
return structure;
}
// parseHTMLFromString(str); // ["<div>", "<ul id="list">", "<li class="something">", "this is the text"]
I am trying to extract a number from a string with regular expression as I am told this would be the best approach for what I am wanting to do.
Here is the string:
http://domain.com/uploads/2011/09/1142_GF-757-S-white.jpg&h=208&w=347&zc=1&q=90&a=c&s=&f=&cc=&ct=
and I am trying to extract 208 from (height) from the string. so I know I have to look for "&h=" in the expression but I don't know what to do after that. How can I match between that and the next "&" but not include them as well...
Thanks..
Regular expression to match an h url parameter containing an integer value.
[&?]h=(\d+)
The Javascript:
var match = /[&?]h=(\d+)/.exec(url_string);
alert(match[1]);
Learn more about Regular Expressions.
To get the entire h=xxxx parameter, you can use this generic function (which you can reuse elsewhere for other purposes) and pass it the desired key:
function getParameterFromURL(url, key) {
var re = new RegExp("[&?]" + key + "=([^&]*)");
var matches = url.match(re);
if (matches) {
return(matches[1]);
}
return(null);
}
var url = "http://domain.com/uploads/2011/09/1142_GF-757-S-white.jpg&h=208&w=347&zc=1&q=90&a=c&s=&f=&cc=&ct=";
var parm = getParameterFromURL(url, "h");
See http://jsfiddle.net/jfriend00/86MEy/ for a working demo.