Develop Reference

How to get parameter value inside a string?

Here's a thing i've been trying to resolve...
We've got some data from an ajax call and the result data is between other stuff a huge string with key:value data. For example:
"2R=OK|2M=2 row(s) found|V1=1,2|"
Is it posible for js to do something like:
var value = someFunction(str, param);
so if i search for "V1" parameter it will return "1,2"
I got this running on Sql server no sweat, but i'm struggling with js to parse the string.
So far i'm able to do this by a VERY rudimentary for loop like this:
var str = "2R=OK|2M=2 row(s) found|V1=1,2|";
var param = "V1";
var arr = str.split("|");
var i = 0;
var value = "";
for(i = 0; i<arr.length; ++i){
if( arr[i].indexOf(param)>-1 ){
value = arr[i].split("=")[1];
}
}
console.log(value);
if i put that into a function it works, but i wonder if there's a more efficient way to do it, maybe some regex? but i suck at it. Hopefully somebody may shine a light on this for me?
Thanks!

This seems to work for your specific use-case:
function getValueByKey(haystack, needle) {
if (!haystack || !needle) {
return false;
}
else {
var re = new RegExp(needle + '=(.+)');
return haystack.match(re)[1];
}
}
var str = "2R=OK|2M=2 row(s) found|V1=1,2|",
test = getValueByKey(str, 'V1');
console.log(test);
JS Fiddle demo.
And, to include the separator in your search (in order to prevent somethingElseV1 matching for V1):
function getValueByKey(haystack, needle, separator) {
if (!haystack || !needle) {
return false;
}
else {
var re = new RegExp('\\' + separator + needle + '=(.+)\\' + separator);
return haystack.match(re)[1];
}
}
var str = "2R=OK|2M=2 row(s) found|V1=1,2|",
test = getValueByKey(str, 'V1', '|');
console.log(test);
JS Fiddle demo.
Note that this approach does require the use of the new RegExp() constructor (rather than creating a regex-literal using /.../) in order to pass variables into the regular expression.
Similarly, because we're using a string to create the regular expression within the constructor, we need to double-escape characters that require escaping (escaping first within the string and then escaping within in the created RegExp).
References:
RegExp.
String.match().

This should work for you and it's delimiters are configurable (if you wish to parse a similar string with different delimiters, you can just pass in the delimiters as arguments):
var parseKeyValue = (function(){
return function(str, search, keyDelim, valueDelim){
keyDelim = quote(keyDelim || '|');
valueDelim = quote(valueDelim || '=');
var regexp = new RegExp('(?:^|' + keyDelim + ')' + quote(search) + valueDelim + '(.*?)(?:' + keyDelim + '|$)');
var result = regexp.exec(str);
if(result && result.length > 1)
return result[1];
};
function quote(str){
return (str+'').replace(/([.?*+^$[\]\\(){}|-])/g, "\\$1");
}
})();
Quote function borrowed form this answer
Usage examples:
var str = "2R=OK|2M=2 row(s) found|V1=1,2|";
var param = "V1";
parseKeyValue(str, param); // "1,2"
var str = "2R=OK&2M=2 row(s) found&V1=1,2";
var param = "2R";
parseKeyValue(str, param, '&'); // "OK"
var str =
"2R=>OK\n\
2M->2 row(s) found\n\
V1->1,2";
var param = "2M";
parseKeyValue(str, param, '\n', '->'); // "2 row(s) found"

Here is another approach:
HTML:
<div id="2R"></div>
<div id="2M"></div>
<div id="V1"></div>
Javascript:
function createDictionary(input) {
var splittedInput = input.split(/[=|]/),
kvpCount = Math.floor(splittedInput.length / 2),
i, key, value,
dictionary = {};
for (i = 0; i < kvpCount; i += 1) {
key = splittedInput[i * 2];
value = splittedInput[i * 2 + 1];
dictionary[key] = value;
}
return dictionary;
}
var input = "2R=OK|2M=2 row(s) found|V1=1,2|",
dictionary = createDictionary(input),
div2R = document.getElementById("2R"),
div2M = document.getElementById("2M"),
divV1 = document.getElementById("V1");
div2R.innerHTML = dictionary["2R"];
div2M.innerHTML = dictionary["2M"];
divV1.innerHTML = dictionary["V1"];
Result:
OK
2 row(s) found
1,2

Remove a character at a certain position in a string - javascript [duplicate]

This question already has answers here:
How can I remove a character from a string using JavaScript?
(22 answers)
Closed 5 years ago.
Is there an easy way to remove the character at a certain position in javascript?
e.g. if I have the string "Hello World", can I remove the character at position 3?
the result I would be looking for would the following:
"Helo World"
This question isn't a duplicate of How can I remove a character from a string using JavaScript?, because this one is about removing the character at a specific position, and that question is about removing all instances of a character.

It depends how easy you find the following, which uses simple String methods (in this case slice()).
var str = "Hello World";
str = str.slice(0, 3) + str.slice(4);
console.log(str)

You can try it this way:
var str = "Hello World";
var position = 6; // its 1 based
var newStr = str.substring(0, position - 1) + str.substring(position, str.length);
alert(newStr);
Here is a live example: http://jsbin.com/ogagaq

Turn the string into array, cut a character at specified index and turn back to string
let str = 'Hello World'.split('')
str.splice(3, 1)
str = str.join('')
// str = 'Helo World'.

If you omit the particular index character then use this method
function removeByIndex(str,index) {
return str.slice(0,index) + str.slice(index+1);
}
var str = "Hello world", index=3;
console.log(removeByIndex(str,index));
// Output: "Helo world"

var str = 'Hello World';
str = setCharAt(str, 3, '');
alert(str);
function setCharAt(str, index, chr)
{
if (index > str.length - 1) return str;
return str.substr(0, index) + chr + str.substr(index + 1);
}

you can use substring() method. ex,
var x = "Hello world"
var x = x.substring(0, i) + 'h' + x.substring(i+1);

Hi starbeamrainbowlabs ,
You can do this with the following:
var oldValue = "pic quality, hello" ;
var newValue = "hello";
var oldValueLength = oldValue.length ;
var newValueLength = newValue.length ;
var from = oldValue.search(newValue) ;
var to = from + newValueLength ;
var nes = oldValue.substr(0,from) + oldValue.substr(to,oldValueLength);
console.log(nes);
I tested this in my javascript console so you can also check this out
Thanks

var str = 'Hello World',
i = 3,
result = str.substr(0, i-1)+str.substring(i);
alert(result);
Value of i should not be less then 1.

JS .replace place b tag in string where == string [duplicate]

This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Case insensitive string replacement in JavaScript?
I am trying to highlight part of a string where it is equal to another variable value.
For example
var string = 'This Is A Test String';
var findWord = 'test';
result should be
'This Is A <b>Test</b> String'
Please note the case insensitive and that I require the use of using variables to pass the 'find/Replace word'
reason I need to do it this was is to keep the exact form/case of the string found where is == to the search word.
In PHP, this works, so basically I'm after the JS equivalent of
preg_replace('/('.$search.')/i','<b>$1</b>',$val['name'])
I'm not good when it comes to regex, this should be simple for someone.

I'd suggest:
var string = "This is a test string.",
needle = "test",
re = new RegExp(needle, "gi"),
newString = string.replace(re, "<strong>" + needle + "</strong>");
console.log(newString);
JS Fiddle demo.
Note that I used <strong></strong> rather than <b></b> (deliberately), though, of course, you can use whatever element-type you like. Also, the gi flags:
g is for a global search, rather than simply stopping at the first match, and
i is for case-insensitive, so 'test' will match Test,tESt and so on...
Edited to preserve capitalization of the matched string/substring:
var string = "This is a Test string.",
needle = "test",
re = new RegExp(needle, "gi"),
newString = string.replace(re, function(a,b){
return "<strong>" + a + "</strong>";
});
document.getElementById('input').appendChild(document.createTextNode(string));
document.getElementById('result').innerHTML = newString;
JS Fiddle demo.
Edited to create a more functional/reusable approach:
function formatMatches(el, needle, wrapper) {
if (!el || !needle) {
return false;
}
else {
var re = new RegExp(needle, "gi"),
haystack = el.textContent,
o = '<' + wrapper + '>',
c = '</' + wrapper + '>';
return haystack.replace(re, function(a) {
return o + a + c;
});
}
}
var needle = "test",
el = document.getElementById('input'),
wrapper = 'strong';
document.getElementById('result').innerHTML = formatMatches(el, needle, wrapper);
JS Fiddle demo.
References:
node.appendChild().
document.createTextNode().
RegExp().
string.replace().

var str = 'This Is A Test String';
var w = 'test';
var result = str.replace(new RegExp(w, 'gi'), function(match) {
return "<b>" + match + "</b>";
});
EDIT: Or, as suggested by the comment, the last line could be replaced by:
var result = str.replace(new RegExp(w, 'gi'), "<b>$&</b>");

Remove all occurrences except last?

I want to remove all occurrences of substring = . in a string except the last one.
E.G:
1.2.3.4
should become:
123.4

You can use regex with positive look ahead,
"1.2.3.4".replace(/[.](?=.*[.])/g, "");

2-liner:
function removeAllButLast(string, token) {
/* Requires STRING not contain TOKEN */
var parts = string.split(token);
return parts.slice(0,-1).join('') + token + parts.slice(-1)
}
Alternative version without the requirement on the string argument:
function removeAllButLast(string, token) {
var parts = string.split(token);
if (parts[1]===undefined)
return string;
else
return parts.slice(0,-1).join('') + token + parts.slice(-1)
}
Demo:
> removeAllButLast('a.b.c.d', '.')
"abc.d"
The following one-liner is a regular expression that takes advantage of the fact that the * character is greedy, and that replace will leave the string alone if no match is found. It works by matching [longest string including dots][dot] and leaving [rest of string], and if a match is found it strips all '.'s from it:
'a.b.c.d'.replace(/(.*)\./, x => x.replace(/\./g,'')+'.')
(If your string contains newlines, you will have to use [.\n] rather than naked .s)

You can do something like this:
var str = '1.2.3.4';
var last = str.lastIndexOf('.');
var butLast = str.substring(0, last).replace(/\./g, '');
var res = butLast + str.substring(last);
Live example:
http://jsfiddle.net/qwjaW/

You could take a positive lookahead (for keeping the last dot, if any) and replace the first coming dots.
var string = '1.2.3.4';
console.log(string.replace(/\.(?=.*\.)/g, ''));

A replaceAllButLast function is more useful than a removeAllButLast function. When you want to remove just replace with an empty string:
function replaceAllButLast(str, pOld, pNew) {
var parts = str.split(pOld)
if (parts.length === 1) return str
return parts.slice(0, -1).join(pNew) + pOld + parts.slice(-1)
}
var test = 'hello there hello there hello there'
test = replaceAllButLast(test, ' there', '')
console.log(test) // hello hello hello there

Found a much better way of doing this. Here is replaceAllButLast and appendAllButLast as they should be done. The latter does a replace whilst preserving the original match. To remove, just replace with an empty string.
var str = "hello there hello there hello there"
function replaceAllButLast(str, regex, replace) {
var reg = new RegExp(regex, 'g')
return str.replace(reg, function(match, offset, str) {
var follow = str.slice(offset);
var isLast = follow.match(reg).length == 1;
return (isLast) ? match : replace
})
}
function appendAllButLast(str, regex, append) {
var reg = new RegExp(regex, 'g')
return str.replace(reg, function(match, offset, str) {
var follow = str.slice(offset);
var isLast = follow.match(reg).length == 1;
return (isLast) ? match : match + append
})
}
var replaced = replaceAllButLast(str, / there/, ' world')
console.log(replaced)
var appended = appendAllButLast(str, / there/, ' fred')
console.log(appended)
Thanks to #leaf for these masterpieces which he gave here.

You could reverse the string, remove all occurrences of substring except the first, and reverse it again to get what you want.

function formatString() {
var arr = ('1.2.3.4').split('.');
var arrLen = arr.length-1;
var outputString = '.' + arr[arrLen];
for (var i=arr.length-2; i >= 0; i--) {
outputString = arr[i]+outputString;
}
alert(outputString);
}
See it in action here: http://jsbin.com/izebay

var s='1.2.3.4';
s=s.split('.');
s.splice(s.length-1,0,'.');
s.join('');
123.4

Search and replace specific query string parameter value in javascript

I have a string which is something like this :
a_href= "www.google.com/test_ref=abc";
I need to search for test_ref=abc in thisabove strinng and replace it with new value
var updated_test_ref = "xyz";
a_href ="www.google.com/test_ref=updated_test_ref"
i.e
www.google.com/test_ref=xyz.
How can we do this ?
EDIT:
test_ref value can be a URL link in itself something like http://google.com?param1=test1&param2=test2. I need to capture complete value not till first &.

a_href = a_href.replace(/(test_ref=)[^\&]+/, '$1' + updated_test_ref);

Based on this discussion I have fixed the Chris function (problem with regex string!)
function updateUrlParameter(url, param, value){
var regex = new RegExp('('+param+'=)[^\&]+');
return url.replace( regex , '$1' + value);
}

Based on this discussion I have created a references function. enjoy
updateUrlParameter(url, param, value){
var regex = new RegExp("/([?|&]" + param + "=)[^\&]+/");
return url.replace(regex, '$1' + value);
}

I was searching for this solution for few hours and finally stumbled upon this question. I have tried all the solutions here. But there is still an issue while replacing specific param value in url.
Lets take a sample url like
http://google.com?param1=test1&param2=test2&anotherparam1=test3
and the updated url should be like
http://google.com?param1=newtest&param2=test2&anotherparam1=test3, where value of param1 is changed.
In this case, as #Panthro has pointed out, adding [?|&] before the querying string ensures that anotherparam1 is not replaced. But this solution also adds the '?' or '&' character to the matching string. So while replacing the matched characters, the '?' or '&' will also get replaced. You will not know exactly which character is replaced so you cannot append that character as well.
The solution is to match '?' or '&' as preceding characters only.
I have re-written the function of #Chris, fixing the issue with string and have added case insensitive argument.
updateUrlParameter(url, param, value){
var regex = new RegExp('(?<=[?|&])(' + param + '=)[^\&]+', 'i');
// return url.replace(regex, param + '=$1' + value);
return url.replace(regex, param + '=' + value);
}
Here (?<=[?|&]) means, the regex will match '?' or '&' char and will take the string that occurs after the specified character (looks behind the character). That means only param1=test1 substring will be matched and replaced.

I know this is a bit dirty code but I've achieved what I was looking for. It replaces the given query string or adds new one if it doesn't exist yet.
function updateUrlParameter(url, param, value) {
var index = url.indexOf("?");
if (index > 0) {
var u = url.substring(index + 1).split("&");
var params = new Array(u.length);
var p;
var found = false;
for (var i = 0; i < u.length; i++) {
params[i] = u[i].split("=");
if (params[i][0] === param) {
params[i][1] = value;
found = true;
}
}
if (!found) {
params.push(new Array(2));
params[params.length - 1][0] = param;
params[params.length - 1][1] = value;
}
var res = url.substring(0, index + 1) + params[0][0] + "=" + params[0][1];
for (var i = 1; i < params.length; i++) {
res += "&" + params[i][0] + "=" + params[i][1];
}
return res;
} else {
return url + "?" + param + "=" + value;
}
}
It will work when given regular URL addresses like:
updateUrlParameter('https://www.example.com/some.aspx?mid=1&id=2','id','5');
updateUrlParameter('https://www.example.com/?mid=1&id=2','id','5');
updateUrlParameter('https://www.example.com/some.aspx','id','5');
Please note It will NOT work only if any of the query string parameter name or value contains "=" and/or "&" chars. It will work just fine behind that.

*Java script code to find a specific query string and replace its value *
('input.letter').click(function () {
//0- prepare values
var qsTargeted = 'letter=' + this.value; //"letter=A";
var windowUrl = '';
var qskey = qsTargeted.split('=')[0];
var qsvalue = qsTargeted.split('=')[1];
//1- get row url
var originalURL = window.location.href;
//2- get query string part, and url
if (originalURL.split('?').length > 1) //qs is exists
{
windowUrl = originalURL.split('?')[0];
var qs = originalURL.split('?')[1];
//3- get list of query strings
var qsArray = qs.split('&');
var flag = false;
//4- try to find query string key
for (var i = 0; i < qsArray.length; i++) {
if (qsArray[i].split('=').length > 0) {
if (qskey == qsArray[i].split('=')[0]) {
//exists key
qsArray[i] = qskey + '=' + qsvalue;
flag = true;
break;
}
}
}
if (!flag)// //5- if exists modify,else add
{
qsArray.push(qsTargeted);
}
var finalQs = qsArray.join('&');
//6- prepare final url
window.location = windowUrl + '?' + finalQs;
}
else {
//6- prepare final url
//add query string
window.location = originalURL + '?' + qsTargeted;
}
})
});