前言

URLSearchParams可以了解一下。本期英文由@Antonio Santiago分享。

英文从这开始～～

No matter if you work with JavaScript at client or server side, at some point you'll need to work with urls and its query params.

As example, I'm currently using react-router in my project, which is an great tool. I can define dynamic routes with path params and easily react-router returns me these params within the match variable and the rest of url information in the location variable, but how can I easily access to query params?

There are great libraries for this purpose -like query-string or qs- but the question is: why increase in some more bytes the size of your package when there is a native solution? 😄 The URLSearchParams.

Detect feature support

As all native implementation remember the support depends on the browser version. See compatibilities here. We can check it with:

1. if(window.URLSearchParams) {

2. // Support :)

3. }

Construct an instance

The most typical usage is to build an URLSearchParams instance from a query string. Note it is also valid to pass a string that start with ?, the URLSearchParams will strip it out:

1. constparams= newURLSearchParams('version=1&name=john&lastname=nieve')

2. // or

3. constparams= newURLSearchParams('?version=1&name=john&lastname=nieve')

🤓 Be aware to not pass string url! Or it will be interpreted as the parameter name. For example, given:

1. constparams= newURLSearchParams('https://some_api.com?paramA=valueA')

You'll get the three parameters named: https://some_api.com?paramA with value valueA.

Working with params

Once we have an instance it is easy to get or set the parameters values:

1. params.get('version') // 1

2. params.get('name') // john

3. params.get('name') // john

4. 
   

5. params.set('lastname', 'stark')

6. params.get('lastname') // stark

7. 
   

8. params.has('lastname') // true

9. params.has('age') // false

We can also add new parameters and work with array parameters:

1. params.set('tags', 'bastard')

2. params.append('tags', 'lord')

3. 
   

4. params.get('tags') // bastard

5. params.getAll('tags') // ['bastard', 'lord']

Note the difference between get and getAll when working with array parameters.

Or simply delete params:

1. params.delete('lastname')

Finally we can convert the URLSearchParams back into a string with the:

1. params.toString() // version=1&name=john&tags=bastard&tags=lord

Working with URLs

If we have an URL string the easy way to get the params is using the URL object:

1. const url = new URL('https://got-api.com?version=1&name=john&lastname=nieve');

2. constparams= newURLSearchParams(url.search);

3. 
   

4. params.toString() // version=1&name=john&lastname=nieve

关于本文 作者：@Antonio Santiago 原文：https://www.acuriousanimal.com/blog/2019/11/09/urlsearchparams/

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