Clean way to get value from string in Javascript - javascript

I have this string https://pokeapi.co/api/v2/pokemon/6/
I would like to extract the value after pokemon/ in this case 6. This represent Pokémon ids which could span between 1 -> N
I know this is pretty trivial and was wondering a nice solution for future proofing. Here is my solution.
const foo= "https://pokeapi.co/api/v2/pokemon/6/"
const result = foo.split('/') //[ 'https:', '', 'pokeapi.co', 'api', 'v2', 'pokemon', '6', '' ]
const ids = result[6]

You can grab the value after the last / character like so:
const pokemonID = foo.substring(foo.lastIndexOf("/") + 1)
Using String.lastIndexOf to get the final index of the slash character, and then using String.substring with only a single argument to parse the part of the string after that last / character. We add 1 to the lastIndexOf to omit the final slash.
For this to work you need to drop your final trailing slash (which won't do anything anyways) from your request URL.
This could be abstracted into a utility function to get the last value of any url, which is the biggest improvement over using a split and find by index approach.
However, beware, it will take whatever the value is after the last slash.
Using the string https://pokeapi.co/api/v2/pokemon/6/pokedex would return pokedex.
If you are using Angular, React, Vue etc with built in router, there will be specific APIs for the framework that can get the exact parameter you need regardless of URL shape.

You should use the built-in URL API to do the splitting correctly for you:
const url = new URL("https://pokeapi.co/api/v2/pokemon/6/");
Then you can get the pathname and split that:
const path = url.pathname.split("/");
After you split it you can get the value 6 by accessing the 5th element here:
const url = new URL("https://pokeapi.co/api/v2/pokemon/6/");
const path = url.pathname.split("/");
console.log(path[4]);

you could also do something like:
url.split('pokemon/')[1].split('/')[0]

Here is what I would do
const result = new URL(url).pathname.split('/');
const id = result[4];

I am not sure if this is better than yours
const foo= "https://pokeapi.co/api/v2/pokemon/6/"
const result = foo.indexOf("pokemon/");
const id_index = result + 8
const id = foo[id_index];

Related

Extracting a certain value from the URL

What do you think will be the most optimal way to extract the value from the window.location.href.
This is the example http://localhost:3000/brand/1/brandCategory/3
the Route will always be the same, just the numbers will change depending on what is chosen.
the brand id will be the first number and the category id is the second I need help extracting them in a react/typescript project.
keep in mind that it should work when the page is deployed and that the start of the URL will have a different name than localhost, but the routes will be the same.
I tried doing it with string formatting, but it's really unpredictable, tried also with regex but when I try to extract it typescript cries about the object is possibly 'null', what can you suggest?
Number(window.location.href.match(new RegExp(/\/[0-9]\//,'gm'))[0].split('/')[1])
this is the regex try.
You can split the path, remove empty segments and retrieve the numbers by position:
const url = 'http://localhost:3000/brand/1/brandCategory/3';
const segments = url.split('/').filter(seg => seg);
const length = segments.length;
console.log(`brand: ${segments[length - 3]}, brandCategory: ${segments[length - 1]}`);
I added the filter for the case of a trailing slash.
You could replace the filter with endsWith
const url = 'http://localhost:3000/brand/1/brandCategory/3';
const segments = url.split('/');
const length = url.endsWith('/') ? segments.length - 1 : segments.length;
console.log(`brand: ${segments[length - 3]}, brandCategory: ${segments[length - 1]}`);

Array contains string the other way

Lets say I have this array
const urlList = ["/user/profile", "/user/edit", "/verify/device"];
const isContainUrl = fruits.includes(window.location.pathname);
That is fine if pathname is static like above, what if I have url like /verify/device/{device-id} , I want isContainUrl to be true as well for partial match. But since I am comparing longer string to the shorter one, so I cant simple use indexOf.
May be anyone has any idea to do it?
It is possible to use some() and check both edge cases:
const urlList = ["/user/profile", "/user/edit", "/verify/device"];
const veryLongString = '/verify/device/1';
const isContainUrl = urlList.some(s => s.includes(veryLongString)
|| veryLongString.includes(s));
console.log(isContainUrl)
You need to parse url according to custom rules, or do some regular matching work.
Refer to path-to-regexp.

URL Parse Exercise (JavaScript)

So here is a description of the problem that I've been talked to solve:
We need some logic that extracts the variable parts of a url into a hash. The keys
of the extract hash will be the "names" of the variable parts of a url, and the
values of the hash will be the values. We will be supplied with:
A url format string, which describes the format of a url. A url format string
can contain constant parts and variable parts, in any order, where "parts"
of a url are separated with "/". All variable parts begin with a colon. Here is
an example of such a url format string:
'/:version/api/:collection/:id'
A particular url instance that is guaranteed to have the format given by
the url format string. It may also contain url parameters. For example,
given the example url format string above, the url instance might be:
'/6/api/listings/3?sort=desc&limit=10'
Given this example url format string and url instance, the hash we want that
maps all the variable parts of the url instance to their values would look like this:
{
version: 6,
collection: 'listings',
id: 3,
sort: 'desc',
limit: 10
}
So I technically have a semi-working solution to this but, my questions are:
Am I understanding the task correctly? I'm not sure if I'm supposed to be dealing with two inputs (URL format string and URL instance) or if I'm just supposed to be working with one URL as a whole. (my solution takes two separate inputs)
In my solution, I keep reusing the split() method to chunk the array/s down and it feels a little repetitive. Is there a better way to do this?
If anyone can help me understand this challenge better and/or help me clean up my solution, it would be greatly appreciated!
Here is my JS:
const obj = {};
function parseUrl(str1, str2) {
const keyArr = [];
const valArr = [];
const splitStr1 = str1.split("/");
const splitStr2 = str2.split("?");
let val1 = splitStr2[0].split("/");
let val2 = splitStr2[1].split("&");
splitStr1.forEach((i) => {
keyArr.push(i);
});
val1.forEach((i) => {
valArr.push(i);
});
val2.forEach((i) => {
keyArr.push(i.split("=")[0]);
valArr.push(i.split("=")[1]);
});
for (let i = 0; i < keyArr.length; i++) {
if (keyArr[i] !== "" && valArr[i] !== "") {
obj[keyArr[i]] = valArr[i];
}
}
return obj;
};
console.log(parseUrl('/:version/api/:collection/:id', '/6/api/listings/3?sort=desc&limit=10'));
And here is a link to my codepen so you can see my output in the console:
https://codepen.io/TOOTCODER/pen/yLabpBo?editors=0012
Am I understanding the task correctly? I'm not sure if I'm supposed to
be dealing with two inputs (URL format string and URL instance) or if
I'm just supposed to be working with one URL as a whole. (my solution
takes two separate inputs)
Yes, your understanding of the problem seems correct to me. What this task seems to be asking you to do is implement a route parameter and a query string parser. These often come up when you want to extract data from part of the URL on the server-side (although you don't usually need to implement this logic your self). Do keep in mind though, you only want to get the path parameters if they have a : in front of them (currently you're retrieving all values for all), not all parameters (eg: api in your answer should be excluded from the object (ie: hash)).
In my solution, I keep reusing the split() method to chunk the array/s
down and it feels a little repetitive. Is there a better way to do
this?
The number of .split() methods that you have may seem like a lot, but each of them is serving its own purpose of extracting the data required. You can, however, change your code to make use of other array methods such as .map(), .filter() etc. to cut your code down a little. The below code also considers the case when no query string (ie: ?key=value) is provided:
function parseQuery(queryString) {
return queryString.split("&").map(qParam => qParam.split("="));
}
function parseUrl(str1, str2) {
const keys = str1.split("/")
.map((key, idx) => [key.replace(":", ""), idx, key.charAt(0) === ":"])
.filter(([,,keep]) => keep);
const [path, query = ""] = str2.split("?");
const pathParts = path.split("/");
const entries = keys.map(([key, idx]) => [key, pathParts[idx]]);
return Object.fromEntries(query ? [...entries, ...parseQuery(query)] : entries);
}
console.log(parseUrl('/:version/api/:collection/:id', '/6/api/listings/3?sort=desc&limit=10'));
It would be even better if you don't have to re-invent the wheel, and instead make use of the URL constructor, which will allow you to extract the required information from your URLs more easily, such as the search parameters, this, however, requires that both strings are valid URLs:
function parseUrl(str1, str2) {
const {pathname, searchParams} = new URL(str2);
const keys = new URL(str1).pathname.split("/")
.map((key, idx) => [key.replace(":", ""), idx, key.startsWith(":")])
.filter(([,,keep]) => keep);
const pathParts = pathname.split("/");
const entries = keys.map(([key, idx]) => [key, pathParts[idx]]);
return Object.fromEntries([...entries, ...searchParams]);
}
console.log(parseUrl('https://www.example.com/:version/api/:collection/:id', 'https://www.example.com/6/api/listings/3?sort=desc&limit=10'));
Above, we still need to write our own custom logic to obtain the URL parameters, however, we don't need to write any logic to extract the query string data as this is done for us by using URLSearchParams. We're also able to lower the number of .split()s used as we can obtain use the URL constructor to give us an object with a parsed URL already. If you end up using a library (such as express), you will get the above functionality out-of-the-box.

Javascript regex parse complex url string

I need to parse a complex URL string to fetch specific values.
From the following URL string:
/api/rss/feeds?url=http://any-feed-url-a.com?filter=hot&format=rss&url=http://any-feed-url-b.com?filter=rising&format=rss
I need to extract this result in array format:
['http://any-feed-url-a.com?filter=hot&format=rss', 'http://any-feed-url-b.com?filter=rising&format=rss']
I tried already with this one /url=([^&]+)/ but I can't capture all correctly all the query parameters. And I would like to omit the url=.
RegExr link
Thanks in advance.
This regex works for me: url=([a-z:/.?=-]+&[a-z=]+)
also, you can test this: /http(s)?://([a-z-.?=&])+&/g
const string = '/api/rss/feeds?url=http://any-feed-url.com?filter=hot&format=rss&url=http://any-feed-url.com?filter=latest&format=rss'
const string2 = '/api/rss/feeds?url=http://any-feed-url.com?filter=hot&format=rss&next=parm&url=http://any-feed-url.com?filter=latest&format=rss'
const regex = /url=([a-z:/.?=-]+&[a-z=]+)/g;
const regex2 = /http(s)?:\/\/([a-z-.?=&])+&/g;
console.log(string.match(regex))
console.log(string2.match(regex2))
have you tried to use split method ? instead of using regex.
const urlsArr = "/api/rss/feeds?url=http://any-feed-url-a.com?filter=hot&format=rss&url=http://any-feed-url-b.com?filter=rising&format=rss".split("url=");
urlsArr.shift(); // removing first item from array -> "/api/rss/feeds?"
console.log(urlsArr)
)
which is going to return ["/api/rss/feeds?", "http://any-feed-url-a.com?filter=hot&format=rss&", "http://any-feed-url-b.com?filter=rising&format=rss"] then i am dropping first item in array
if possible its better to use something else then regex CoddingHorror: regular-expressions-now-you-have-two-problems
You can matchAll the url's, then map the capture group 1 to an array.
str = '/api/rss/feeds?url=http://any-feed-url-a.com?filter=hot&format=rss&url=http://any-feed-url-b.com?filter=rising&format=rss'
arr = [...str.matchAll(/url=(.*?)(?=&url=|$)/g)].map(x => x[1])
console.log(arr)
But matchAll isn't supported by older browsers.
But looping an exec to fill an array works also.
str = '/api/rss/feeds?url=http://any-feed-url-a.com?filter=hot&format=rss&url=http://any-feed-url-b.com?filter=rising&format=rss'
re = /url=(.*?)(?=&url=|$)/g;
arr = [];
while (m = re.exec(str)) {
arr.push(m[1]);
}
console.log(arr)
If your input is better-formed in reality than shown in the question and you’re targeting a modern JavaScript environment, there’s URL/URLSearchParams:
const input = '/api/rss/feeds?url=http://any-feed-url-a.com?filter=hot%26format=rss&url=http://any-feed-url-b.com?filter=rising%26format=rss';
const url = new URL(input, 'http://example.com/');
console.log(url.searchParams.getAll('url'));
Notice how & has to be escaped as %26 for it to make sense.
Without this input in a standard form, it’s not clear which rules of URLs are still on the table.

Split A string on a term AND THEN splitting on another term

I have a poorly designed URL query string that I can't easily change e.g.
https://mysite/.shtml?source=999&promotype=promo&cmpid=abc--dfg--hif-_-1234&cm=qrs-stv-_wyx&aff=45628_THIS+IS+Test_Example
I need to extract elements from it e.g. 45628
At the moment I'm using
document.URL.split(/aff=|_/)[5];
But I don't like this solution because if other parts of the URL structure change which is highly likely then my solution will break
Instead what I want to say is
split on "aff=" AND THEN split on "_"
Is there an easy way to do this, looking for a JS answer
Pretty sure you can do it like this:
document.URL.split("aff=")[1].split("_")[0];
I would start by splitting the string into tokens, if you can. Rather than working with foo=bar&fin=bin, break it down into [['foo', 'bar'], ['fin', 'bin]]. You can do that by splitting on the & and then the splitting each of those on the = character:
const data = 'source=999&promotype=promo&cmpid=abc--dfg--hif-_-1234&cm=qrs-stv-_wyx&aff=45628_THIS+IS+Test_Example';
console.log(data.split('&').map(it => it.split('=')));
Next, take the tokens you want and extract the leading digits:
const data = 'source=999&promotype=promo&cmpid=abc--dfg--hif-_-1234&cm=qrs-stv-_wyx&aff=45628_THIS+IS+Test_Example';
const tokens = data.split('&').map(it => it.split('='));
const [key,val] = tokens.find(([key]) => key === 'aff');
console.log(key, val.match(/[0-9]+/));
var url = 'https://mysite/.shtml?source=999&promotype=promo&cmpid=abc--dfg--hif-_-1234&cm=qrs-stv-_wyx&aff=45628_THIS+IS+Test_Example';
var re = new RegExp(/aff=(\d+)/);
var ext = re.exec(url)[1];
alert(ext)

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