Develop Reference

replacing last word of string using node js / javascript

var str = "Demo Docs Version 1.0.1";
var got = str.split(" ").splice(-1)[0]
str = str.replace(got, "testing");
console.log(str);
I can replace last word if there is space in between but how can i replace my last word when there _ in string ?
var str = "Demo-Docs-Version-1-0-1";
var got = str.split(" ").splice(-1)[0]
str = str.replace(got, "testing");
console.log(str);

What about this?
str = str.replace(/(?!.*(\s|_)).*/, "testing")

Find and Replace special char with defined value

I want to find and replace if a string contain /,+,?,-,_,# any of these into _sls_,_pls_,_wht_,_dsh_,_usc_,_hsh_ this respectively.
Example:
'_sls_'=>'/','_pls_'=>'+','_wht_'=>'?','_dsh_'=>'-','_usc_'=>'_','_hsh_'=>'#'
Mary_land = Mary_usc_land
Mary+land = Mary_pls_land

Write all the characters you want to get replaced into a function and call it
var string1 = "Mary_land";
var string2 = "Mary+lang";
var string3 = "Mary#lang";
var string4 = "Mary-lang";
var string5 = "Mary/lang?Maryland";
console.log(normalize(string1));
console.log(normalize(string2));
console.log(normalize(string3));
console.log(normalize(string4));
console.log(normalize(string5));
function normalize(str){
str = str.replace(/_/g,"_usc_");
str = str.replace(/\+/g,"_pls_");
str = str.replace(/\//g,"_sls_");
str = str.replace(/#/g,"_hsh_");
str = str.replace(/-/g,"_dsh_");
str = str.replace(/\?/g,"_wht_");
return str;
}

JavaScript Split, Split string by last DOT "."

JavaScript Split,
str = '123.2345.34' ,
expected output 123.2345 and 34
Str = 123,23.34.23
expected output 123,23.34 and 23
Goal : JS function to Split a string based on dot(from last) in O(n).
There may be n number of ,.(commas or dots) in string.

In order to split a string matching only the last character like described you need to use regex "lookahead".
This simple example works for your case:
var array = '123.2345.34'.split(/\.(?=[^\.]+$)/);
console.log(array);
Example with destructuring assignment (Ecmascript 2015)
const input = 'jquery.somePlugin.v1.6.3.js';
const [pluginName, fileExtension] = input.split(/\.(?=[^\.]+$)/);
console.log(pluginName, fileExtension);
However using either slice or substring with lastIndexOf also works, and albeit less elegant it's much faster:
var input = 'jquery.somePlugin.v1.6.3.js';
var period = input.lastIndexOf('.');
var pluginName = input.substring(0, period);
var fileExtension = input.substring(period + 1);
console.log(pluginName, fileExtension);

var str = "filename.to.split.pdf"
var arr = str.split("."); // Split the string using dot as separator
var lastVal = arr.pop(); // Get last element
var firstVal = arr.join("."); // Re-join the remaining substrings, using dot as separator
console.log(firstVal + " and " + lastVal); //Printing result

I will try something like bellow
var splitByLastDot = function(text) {
var index = text.lastIndexOf('.');
return [text.slice(0, index), text.slice(index + 1)]
}
console.log(splitByLastDot('123.2345.34'))
console.log(splitByLastDot('123,23.34.23'))

I came up with this:
var str = '123,23.34.23';
var result = str.replace(/\.([^.]+)$/, ':$1').split(':');
document.getElementById('output').innerHTML = JSON.stringify(result);
<div id="output"></div>

let returnFileIndex = str =>
str.split('.').pop();

Try this:
var str = '123.2345.34',
arr = str.split('.'),
output = arr.pop();
str = arr.join('.');

var test = 'filename.....png';
var lastStr = test.lastIndexOf(".");
var str = test.substring(lastStr + 1);
console.log(str);

I'm typically using this code and this works fine for me.
Jquery:
var afterDot = value.substr(value.lastIndexOf('_') + 1);
console.log(afterDot);
Javascript:
var myString = 'asd/f/df/xc/asd/test.jpg'
var parts = myString.split('/');
var answer = parts[parts.length - 1];
console.log(answer);
Note: Replace quoted string to your own need

My own version:
var mySplit;
var str1;
var str2;
$(function(){
mySplit = function(myString){
var lastPoint = myString.lastIndexOf(".");
str1 = myString.substring(0, lastPoint);
str2 = myString.substring(lastPoint + 1);
}
mySplit('123,23.34.23');
console.log(str1);
console.log(str2);
});
Working fiddle: https://jsfiddle.net/robertrozas/no01uya0/

Str = '123,23.34.23';
var a = Str.substring(0, Str.lastIndexOf(".")) //123,23.34
var b = Str.substring(Str.lastIndexOf(".")) //23

Try this solution.
Simple Spilt logic
<script type="text/javascript">
var str = "123,23.34.23";
var str_array = str.split(".");
for (var i=0;i<str_array.length;i++)
{
if (i == (str_array.length-1))
{
alert(str_array[i]);
}
}
</script>

The simplest way is mentioned below, you will get pdf as the output:
var str = "http://somedomain.com/dir/sd/test.pdf";
var ext = str.split('.')[str.split('.').length-1];
Output: pdf

Javascript regex help

I have the following string in JavaScript
var mystring = " abcdef(p,q); check(x,y); cef(m,n);"
I would want to do a string replace such that my final string is :
mystring = " abcdef(p,q); someothercheck\(x,y\); cef(m,n);"
x and y should remain same after the substitution. and the backslashes are necessary since I need to pass them to some other command.
There can be other Parantheses in the string too.

If you don't have other parenthesis, it should be easy.
mystring = mystring.replace("check(", "someothercheck\\(");
mystring = mystring.replace(")", "\\)");
EDIT This works also in the case of multiple parenthesis (It does not affect the empty ones).
var str=" abcdef; check(x,y); cef();"
patt = /((\w)/g;
// transform (x in \(x
str = str.replace(patt, '\\($1');
patt = /(\w)\)/g
// transform y) in y\);
str = str.replace(patt, '$1\\)');
// transform check in someothercheck
str = str.replace('check', 'someothercheck');
EDIT Now it converts only the check strings.
function convertCheck(str, check, someOtherCheck) {
// console.log(str + " contains " + check + "? ");
// console.log(str.indexOf(check));
if (str.indexOf(check) === -1) return str;
var patt1 = /\((\w)/g,
patt2 = /(\w)\)/g;
str = str.replace(patt1, '\\($1');
str = str.replace(patt2, '$1\\)');
str = str.replace(check, someOtherCheck);
return str;
}
var str = "abcdef(); check(x,y); cef();",
tokens = str.split(';');
for (var i = 0; i < tokens.length; i++) {
tokens[i] = convertCheck(tokens[i], "check", "someothercheck");
}
str = tokens.join(";");
alert(str); // "abcdef(); someothercheck/(x,y/); cef();"

var myString = "abcdef; check(x,y); cef;";
myString.replace(/(\w+)\(/, 'someother$1(')
.replace(/\(/g, '\\(')
.replace(/\)/g, '\\)')

How can I replace a regex substring match in Javascript?

var str = 'asd-0.testing';
var regex = /asd-(\d)\.\w+/;
str.replace(regex, 1);
That replaces the entire string str with 1. I want it to replace the matched substring instead of the whole string. Is this possible in Javascript?

var str = 'asd-0.testing';
var regex = /(asd-)\d(\.\w+)/;
str = str.replace(regex, "$11$2");
console.log(str);
Or if you're sure there won't be any other digits in the string:
var str = 'asd-0.testing';
var regex = /\d/;
str = str.replace(regex, "1");
console.log(str);

using str.replace(regex, $1);:
var str = 'asd-0.testing';
var regex = /(asd-)\d(\.\w+)/;
if (str.match(regex)) {
str = str.replace(regex, "$1" + "1" + "$2");
}
Edit: adaptation regarding the comment

I would get the part before and after what you want to replace and put them either side.
Like:
var str = 'asd-0.testing';
var regex = /(asd-)\d(\.\w+)/;
var matches = str.match(regex);
var result = matches[1] + "1" + matches[2];
// With ES6:
var result = `${matches[1]}1${matches[2]}`;

I think the simplest way to achieve your goal is this:
var str = 'asd-0.testing';
var regex = /(asd-)(\d)(\.\w+)/;
var anyNumber = 1;
var res = str.replace(regex, `$1${anyNumber}$3`);