I have this string:
var s = '/channels/mtb/videos?page=2&per_page=100&fields=uri%2Cname%2Cdescription%2Cduration%2Cwidth%2Cheight%2Cprivacy%2Cpictures.sizes&sort=date&direction=asc&filter=embeddable&filter_embeddable=true'
I want to repace per_page number (in this case 100, but it can be any number from 1-100, maybe more?)
I can select first part of the string with:
var s1 = s.substr(0, s.lastIndexOf('per_page=')+9)
which give me:
/channels/mtb/videos?page=2&per_page=
but how would I select next '&' after that so I can replace number occurrence?
dont assume same order of parameters!
You can use following regex to replace the content you want.
regex:- /per_page=[\d]*/g(this is only for your requirement)
var new_no=12; //change 100 to 12
var x='/channels/mtb/videos?page=2&per_page=100&fields=uri%2Cname%2Cdescription%2Cduration%2Cwidth%2Cheight%2Cprivacy%2Cpictures.sizes&sort=date&direction=asc&filter=embeddable&filter_embeddable=true';
var y=x.replace(/per_page=[\d]*/g,'per_page='+new_no);
console.log(y);
Explanation:-
/per_page=[\d]*/g
/ ----> is for regex pattern(it inform that from next character onward whatever it encounter will be regex pattern)
per_page= ----> try to find 'per_page=' in string
[\d]* ----> match 0 or more digit (it match until non digit encounter)
/g ---->/ to indicate end of regex pattern and 'g' is for global means find in all string(not only first occurrence)
Use replace with a regular expression to find the numbers after the text per_page=. Like this:
s.replace(/per_page=\d+/,"per_page=" + 33)
Replace the 33 with the number you want.
Result:
"/channels/mtb/videos?page=2&per_page=33&fields=uri%2Cname%2Cdescription%2Cduration%2Cwidth%2Cheight%2Cprivacy%2Cpictures.sizes&sort=date&direction=asc&filter=embeddable&filter_embeddable=true"
Start with the index from the lastIndexOf-per_page instead of 0.
Get the index of the first & and create a substr s2 to the end.
Then concat s1 + nr + s2.
I would not use regex, because it is much slower for this simple stuff.
With Array.filter you can do this, where one split the text into key/value pairs, and filter out the one that starts with per_page=.
Stack snippet
var s = '/channels/mtb/videos?page=2&per_page=100&fields=uri%2Cname%2Cdescription%2Cduration%2Cwidth%2Cheight%2Cprivacy%2Cpictures.sizes&sort=date&direction=asc&filter=embeddable&filter_embeddable=true'
var kv_pairs = s.split('&');
var s2 = s.replace((kv_pairs.filter(w => w.startsWith('per_page=')))[0],'per_page=' + 123);
//console.log(s2);
var matches = /(.*\bper_page=)(\d+)(.*)/;
if (matches) {
s = matches[0] + newValue + matches[2];
}
Related
I'm working with a string where I need to extract the first n characters up to where numbers begin. What would be the best way to do this as sometimes the string starts with a number: 7EUSA8889er898 I would need to extract 7EUSA But other string examples would be SWFX74849948, I would need to extract SWFX from that string.
Not sure how to do this with regex my limited knowledge is blocking me at this point:
^(\w{4}) that just gets me the first four characters but I don't really have a stopping point as sometimes the string could be somelongstring292894830982 which would require me to get somelongstring
Using \w will match a word character which includes characters and digits and an underscore.
You could match an optional digit [0-9]? from the start of the string ^and then match 1+ times A-Za-z
^[0-9]?[A-Za-z]+
Regex demo
const regex = /^[0-9]?[A-Za-z]+/;
[
"7EUSA8889er898",
"somelongstring292894830982",
"SWFX74849948"
].forEach(s => console.log(s.match(regex)[0]));
Can use this regex code:
(^\d+?[a-zA-Z]+)|(^\d+|[a-zA-Z]+)
I try with exmaple and good worked:
1- somelongstring292894830982 -> somelongstring
2- 7sdfsdf5456 -> 7sdfsdf
3- 875werwer54556 -> 875werwer
If you want to create function where the RegExp is parametrized by n parameter, this would be
function getStr(str,n) {
var pattern = "\\d?\\w{0,"+n+"}";
var reg = new RegExp(pattern);
var result = reg.exec(str);
if(result[0]) return result[0].substr(0,n);
}
There are answers to this but here is another way to do it.
var string1 = '7EUSA8889er898';
var string2 = 'SWFX74849948';
var Extract = function (args) {
var C = args.split(''); // Split string in array
var NI = []; // Store indexes of all numbers
// Loop through list -> if char is a number add its index
C.map(function (I) { return /^\d+$/.test(I) === true ? NI.push(C.indexOf(I)) : ''; });
// Get the items between the first and second occurence of a number
return C.slice(NI[0] === 0 ? NI[0] + 1 : 0, NI[1]).join('');
};
console.log(Extract(string1));
console.log(Extract(string2));
Output
EUSA
SWFX7
Since it's hard to tell what you are trying to match, I'd go with a general regex
^\d?\D+(?=\d)
I have a string like
5|10|20|200|300
and i want to get the First Digit Before | and last digit after | that is 5 and 300.
How would I use regex in javascript to return that numbers??
This simplest regex will return the two matches 5 and 300:
^\d+|\d+$
See the matches in the demo.
In JS:
result = yourString.match(/^\d+|\d+$/g);
Explanation
^\d+ matches the beginning of the string and some digits (the 5)
OR |
\d+$ matches some digits and the end of the string
JavaScript only keeps the last capture for (...)+, so you can write
var m = "5|10|20|200|300".match(/(\d+)(\|(\d+))+/);
Then m[1] is "5" and m[3] is "300"
var string = '5|10|20|200|300';
var array = string.split('|');
//array[0] = '5';
//array[array.length-1] = '300';
It's not regex I know, but I've always found split easier to work with in most cases.
Convert the string into an array using split() method
var str="5|10|20|200|300";
var res_array = str.split("|");
now to get first and last value of an array:::
alert("First value is"+ res_array[0]);
alert("Last value is"+ res_array[arr.length - 1]);
I only want to remove the first 100 words and keep whats remaining from the string.
The code I have below does the exact opposite:
var short_description = description.split(' ').slice(0,100).join(' ');
Remove the first argument:
var short_description = description.split(' ').slice(100).join(' ');
Using slice(x, y) will give you elements from x to y, but using slice(x) will give you elements from x to the end of the array. (note: this will return the empty string if the description has less than 100 words.)
Here is some documentation.
You could also use a regex:
var short_description = description.replace(/^([^ ]+ ){100}/, '');
Here is an explanation of the regex:
^ beginning of string
( start a group
[^ ] any character that is not a space
+ one or more times
then a space
) end the group. now the group contains a word and a space.
{100} 100 times
Then replace those 100 words with nothing. (note: if the description is less than 100 words, this regex will just return the description unchanged.)
//hii i am getting result using this function
var inputString = "This is file placed on Desktop"
inputString = removeNWords(inputString, 2)
console.log(inputString);
function removeNWords(input,n) {
var newString = input.replace(/\s+/g,' ').trim();
var x = newString.split(" ")
return x.slice(n,x.length).join(" ")
}
The reason this is doing the opposite, is that slice returns the selected elements (in this case, the first one hundred) and returns them in it's own array. To get all of the elements after one hundred, you would have to do something like description.slice(100) to get the split array properly, and then your own join to merge back the array.
var short_description = description.split(' ').slice(100).join(' ');
I have to split the values using JavaScript and want to find the last occuring slash / from a string and replace the contents after the last slash / For example:
var word = "www.abc/def/ghf/ijk/**default.aspx**";
should become
var word ="www.abc/def/ghf/ijk/**replacement**";
The number of slashes may vary each time.
Try using regexp:
"www.abc/def/ghf/ijk/default.aspx".replace(/\/[^\/]+$/, "/replacement");
An alternative without regular expression (I just remembered lastIndexOf() method)
var word = "www.abc/def/ghf/ijk/default.aspx";
word = word.substring(0, word.lastIndexOf("/")) + "/replacement";
You can array split on '/', then pop the last element off the array, and rejoin.
word = word.split('/');
word.pop();
word = word.join('/') + replacement;
How about the KISS principle?
var word = "www.abc/def/ghf/ijk/default.aspx";
word = word.substring(0, word.lastIndexOf("/")) + "/replacement";
What about using a combination of the join() and split() functions?
var word = "www.abc/def/ghf/ijk/default.aspx";
// split the word using a `/` as a delimiter
wordParts = word.split('/');
// replace the last element of the array
wordParts[wordParts.length-1] = 'replacement';
// join the array back to a string.
var finalWord = wordParts.join('/');
The number of slashes doesn't matter here because all that is done is to split the string at every instance of the delimiter (in this case a slash).
Here is a working demo
Use regexp or arrays, something like:
[].splice.call(word = word.split('/'), -1, 1, 'replacement');
word = word.join('/');
I'm trying to split a string into an array based on the second occurrence of the symbol _
var string = "this_is_my_string";
I want to split the string after the second underscore. The string is not always the same but it always has 2 or more underscores in it. I always need it split on the second underscore.
In the example string above I would need it to be split like this.
var split = [this_is, _my_string];
var string = "this_is_my_string";
var firstUnderscore = string.indexOf('_');
var secondUnderscore = string.indexOf('_', firstUnderscore + 1);
var split = [string.substring(0, secondUnderscore),
string.substring(secondUnderscore)];
Paste it into your browser's console to try it out. No need for a jsFiddle.
var string = "this_is_my_string";
var splitChar = string.indexOf('_', string.indexOf('_') + 1);
var result = [string.substring(0, splitChar),
string.substring(splitChar, string.length)];
This should work.
var str = "this_is_my_string";
var matches = str.match(/(.*?_.*?)(_.*)/); // MAGIC HAPPENS HERE
var firstPart = matches[1]; // this_is
var secondPart = matches[2]; // _my_string
This uses regular expressions to find the first two underscores, and captures the part up to it and the part after it. The first subexpression, (.*?_.*?), says "any number of characters, an underscore, and again any number of characters, keeping the number of characters matched as small as possible, and capture it". The second one, (_.*) means "match an underscore, then any number of characters, as much of them as possible, and capture it". The result of the match function is an array starting with the full matched region, followed by the two captured groups.
I know this post is quite old... but couldn't help but notice that no one provided a working solution. Here's one that works:
String str = "this_is_my_string";
String undScore1 = str.split("_")[0];
String undScore2 = str.split("_")[1];
String bothUndScores = undScore1 + "_" + undScore2 + "_";
String allElse = str.split(bothUndScores)[1];
System.out.println(allElse);
This is assuming you know there will always be at least 2 underscores - "allElse" returns everything after the second occurrence.