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Return a subset of String [duplicate]

This question already has answers here:
Last segment of URL with JavaScript
(30 answers)
Closed 3 months ago.
I have this string:
'/api/media-objects/e78c7cfa-e469-4edd-8a87-9517a5b9e5da'
I want to return only the id ('e78c7cfa-e469-4edd-8a87-9517a5b9e5da') after the last '/'. The id changes everytime I make an API call. How can I do that using any String functions?

You could use match() here:
var input = "/api/media-objects/e78c7cfa-e469-4edd-8a87-9517a5b9e5da";
var output = input.match(/[^\/]+$/)[0];
console.log(output);
Another regex option would be to do a replacement:
var input = "/api/media-objects/e78c7cfa-e469-4edd-8a87-9517a5b9e5da";
var output = input.replace(/^.*\//, "");
console.log(output);

You can use String.prototype.split which splits a string based on the given separator:
const path = '/api/media-objects/e78c7cfa-e469-4edd-8a87-9517a5b9e5da'
const parts = path.split('/')
const id = parts[parts.length - 1] // the last chunk
See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/split

You can create a substring from the position of the last / (+ 1 to omit the it) to the end of the string:
str.slice(str.lastIndexOf('/') + 1)
Note: This assumes that the string will always contain a /. If it's possible that it doesn't you have to handle that case.

How to create regular expression in a loop? [duplicate]

This question already has answers here:
Javascript Regex: How to put a variable inside a regular expression? [duplicate]
(9 answers)
Closed 4 years ago.
I currently have a regex that looks like:
const ignoreRegex = new RegExp(/^\/(?!fonts|static).*$/)
However, I also have a dynamic array of strings like "test" which need to be ignored too. I need to somehow map through this array and add each string to the regex, such that:
const ignoreRegex = new RegExp(/^\/(?!fonts|static + ignoreRoutes.map(x => `|${x}`) + ).*$/)
How do I do this?

You can omit the / / surrounding your regular expression and use a string in the RegExp constructor.
See the code below.
const ignoreFolders = ["fonts", "static"];
const ignoreRoutes = ["route1", "route2"];
const ignore = ignoreFolders.concat(ignoreRoutes);
const ignoreRegex = new RegExp(`^\/(?!${ignore.join("|")}).*$`);
console.log(ignoreRegex);
If you have any regex special characters in your string, they will be escaped automatically.

const ignoreRoutes = ["fonts","static","aaa","bbb","ccc"];
const ignoreRegex = new RegExp(`^\\/(?!${ignoreRoutes.join("|")}).*$`);

how to detect and get url on string javascript [duplicate]

This question already has answers here:
Javascript: extract URLs from string (inc. querystring) and return array
(5 answers)
Closed 7 years ago.
how to detect and get url on string javascript?
example :
var string = "hei dude, check this link http:://google.com and http:://youtube.com"
how to get result like this from my string :
var result = ["http:://google.com", "http:://youtube.com"]
how do that?

You input has double :: after http. Not sure if it intentional. If it is then use:
var matches = string.match(/\bhttps?::\/\/\S+/gi);
If only one : is needed then use:
var matches = string.match(/\bhttps?:\/\/\S+/gi);
RegEx Demo

const string = "hei dude, check this link http:://google.com and http:://youtube.com"
const matches = string.match(/\bhttp?::\/\/\S+/gi);
console.log(matches);

Extract specific data from JavaScript .getAttribute() [duplicate]

This question already has answers here:
Parse query string in JavaScript [duplicate]
(11 answers)
Closed 8 years ago.
So let's say I have this HTML link.
<a id="avId" href="http://www.whatever.com/user=74853380">Link</a>
And I have this JavaScript
av = document.getElementById('avId').getAttribute('href')
Which returns:
"http://www.whatever.com/user=74853380"
How do I extract 74853380 specifically from the resulting string?

There are a couple ways you could do this.
1.) Using substr and indexOf to extract it
var str = "www.something.com/user=123123123";
str.substr(str.indexOf('=') + 1, str.length);
2.) Using regex
var str = var str = "www.something.com/user=123123123";
// You can make this more specific for your query string, hence the '=' and group
str.match(/=(\d+)/)[1];
You could also split on the = character and take the second value in the resulting array. Your best bet is probably regex since it is much more robust. Splitting on a character or using substr and indexOf is likely to fail if your query string becomes more complex. Regex can also capture multiple groups if you need it to.

You can use regular expression:
var exp = /\d+/;
var str = "http://www.whatever.com/user=74853380";
console.log(str.match(exp));
Explanation:
/\d+/ - means "one or more digits"
Another case when you need find more than one number
"http://www.whatever.com/user=74853380/question/123123123"
You can use g flag.
var exp = /\d+/g;
var str = "http://www.whatever.com/user=74853380/question/123123123";
console.log(str.match(exp));
You can play with regular expressions

Well, you could split() it for a one liner answer.
var x = parseInt(av.split("=")[1],10); //convert to int if needed

How to remove all characters after a certain index from a string [duplicate]

This question already has answers here:
Remove everything after a certain character
(10 answers)
Closed 9 years ago.
I am trying to remove all characters from a string after a specified index. I am sure there must be a simple function to do this, but I'm not sure what it is. I am basically looking for the javascript equivalent of c#'s string.Remove.

var myStr = "asdasrasdasd$hdghdfgsdfgf";
myStr = myStr.split("$")[0];
or
var myStr = "asdasrasdasd$hdghdfgsdfgf";
myStr = myStr.substring(0, myStr.indexOf("$") - 1);

Use substring
var x = 'get this test';
alert(x.substr(0,8)); //output: get this

You're looking for this.
string.substring(from, to)
from : Required. The index where to start the extraction. First character is at index 0
to : Optional. The index where to stop the extraction. If omitted, it extracts the rest of the string
See here: http://www.w3schools.com/jsref/jsref_substring.asp

I'd recommend using slice as you can use negative positions for the index. It's tidier code in general. For example:
var s = "messagehere";
var message = s.slice(0, -4);