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/, ...)
Related
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.
Hi,
I have this code:
var room = 'room2';
var exitroom = 'room1,room2,room3';
exitroom = exitroom.replace(/,${room},/,'');
console.log(exitroom);
you can try it here: https://jsfiddle.net/uq9w0Ls4/
my expected output is simply room1,room3 by taking room2 out but since it may change its position within the string I want to target the , no matter if it comes before or after the string but I cant figure out the regex logic here. I know I could just do simply:
var room = 'room2';
var exitroom = 'room1,room2,room3';
exitroom = exitroom.replace(room+',','').replace(','+room,'');
console.log(exitroom);
which works but I think regex would be a more direct approach.
Thank you.
First, by writing .replace(/,${room},/,'') you are not using the variable room.
To use a variable in a regex you should call new RegExp()
Second, if you want a regex that will match when the comma is before or after the word, you can use a group () with an Or | operator.
so it should look like this:
var reg = new RegExp(`(?:${room},|,${room})`, "g");
exitroom.replace(reg,'');
The ?: at the beginning of the group, is just so it should be a non-capturing group, it should work just fine also without it
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 have a text string that can be any number of characters that I would like to attach an order number to the end. Then I can pluck off the order number when I need to use it again. Since there's a possibility that the number is variable length, I would like to do a regular expression that catch's everything after the = sign in the string ?order_num=
So the whole string would be
"aijfoi aodsifj adofija afdoiajd?order_num=3216545"
I've tried to use the online regular expression generator but with no luck. Can someone please help me with extracting the number on the end and putting them into a variable and something to put what comes before the ?order_num=203823 into its own variable.
I'll post some attempts of my own, but I foresee failure and confusion.
var s = "aijfoi aodsifj adofija afdoiajd?order_num=3216545";
var m = s.match(/([^\?]*)\?order_num=(\d*)/);
var num = m[2], rest = m[1];
But remember that regular expressions are slow. Use indexOf and substring/slice when you can. For example:
var p = s.indexOf("?");
var num = s.substring(p + "?order_num=".length), rest = s.substring(0, p);
I see no need for regex for this:
var str="aijfoi aodsifj adofija afdoiajd?order_num=3216545";
var n=str.split("?");
n will then be an array, where index 0 is before the ? and index 1 is after.
Another example:
var str="aijfoi aodsifj adofija afdoiajd?order_num=3216545";
var n=str.split("?order_num=");
Will give you the result:
n[0] = aijfoi aodsifj adofija afdoiajd and
n[1] = 3216545
You can substring from the first instance of ? onward, and then regex to get rid of most of the complexities in the expression, and improve performance (which is probably negligible anyway and not something to worry about unless you are doing this over thousands of iterations). in addition, this will match order_num= at any point within the querystring, not necessarily just at the very end of the querystring.
var match = s.substr(s.indexOf('?')).match(/order_num=(\d+)/);
if (match) {
alert(match[1]);
}
I am new to Javascript and recently I wanted to use regular expression in order to get a number from url and store it into a var as string and another var as digit. For example I want to get the number 55 from the below webpage (which is not an accrual page) and I want to store it in a var.
I tried this but it is not working
https://www.google.com/55.html
url.replace(/(\d+)(\.html)$/, function(str, p1, p2) {
return((Number(p1) + 1) + p2);
Please I need help but not with jQuery because it does not make a lot of sense to me.
var numPortion = url.match(/(\d+)\.html/)[1]
(Assumes a match; if it might not match, check the results before applying the array subscript.)
Try this
var a="https://www.google.com/55.html";
var match = a.match(/(\d+)(\.html)/);
match is an array,
match[0] contains the matched expression from your script,
match[1] is the number (the 1st parenthesis),
and so on
var url = 'http://www.google.com/55.html';
var yournumber = /(\d+)(\.html)$/.exec(url);
yournumber = yournumber && yournumber[1]; // <-- shortcut for using if else