@loadingio/ldquery

lightweight DOM Helpers in Vanilla JS.

Installation

install via npm:

npm install @loadingio/ldquery

or, download it from github:

https://github.com/loadingio/ldquery/releases/latest/download/ldq.js
https://github.com/loadingio/ldquery/releases/latest/download/ldq.min.js

or use it directly via CDN:

https://cdn.jsdelivr.net/gh/loadingio/[email protected]/dist/ldq.js
https://cdn.jsdelivr.net/gh/loadingio/[email protected]/dist/ldq.min.js

in you html, include it directly with <script> tag:

<script src="https://cdn.jsdelivr.net/gh/loadingio/[email protected]/dist/ldq.min.js"></script>

Usage

ldquery provides following functions:

• find(node, selector, index): shorthand for querySelector and querySelectorAll. return array when index is omitted.

• index(node): index of node in childNodes of its parent.

• child(node): children of node, in Array.

• parent(node, selector, endNode): search parent(including node) for which matching the selector, until endNode is reached. return null if not found.

• attr(node, name, value): get attribute "name" if value is omitted. set attribute if value is provided.

• on(node, name, callback): addEventListener on event name.

• remove(node): remove node from parent.

• insertAfter(node, newNode, oldNode): insert newNode after oldNode under node.

• fetch: fetch API helper.

• xhr: XMLHttpRequest API helper.

• json(data): handy function to convert things to object.

• cls(o,p,n): handy function for setting classes.

  • o: either object or value.
    • object: class name / on,off pair
    • value: true to toggle classes in p on, and classes in n off. vice versa.
  • p: positive class list ( toggled when o is true )
  • n: negative class list ( toggled when o is false ) invoke these functions with ld$, e.g.,

  ld$.find(document.body, '.btn', 0)

or ignore the first parameter if it's document:

ld$.find('.btn', 0)  /* equivalent to ld$.find(document, '.btn', 0) */

It also provides in wrapper style:

ld$(document.body).find('.btn', 0)

While it's not a good idea but you can pollute the native DOM for a more intuitive way to use these functions:

# in livescript syntax
HTMLElement.prototype <<< ld$obj.prototype

This could be enabled by remove the comment mark in corresponding line inside ldq.ls.

Fetch

ldquery wraps fetch api with promise-based error handling and some additional parameter.

ld$.fetch(<URL>, <RAWOPTION>, <LDQOPTION>)
  .then ->  ...
  .catch (e) -> # use e.data to get raw response from fetch

Common raw options:

• method: HTTP method. e.g., "POST"
• body: things to send to server. pass JSON by stringify it.
  • ld$.fetch "url", {body: JSON.stringify({data: 1})}
• headers: header hash. customize your own header here.

Common ldquery Options:

• type: indicate the response data type. could be text or json.
• json: json object to pass. shorthand for manually setting headers and stringify object.
  • this: ld$.fetch("url", {}, {json: {data: 1}})
  • is the same with this: ld$.fetch("url", {body: "{data: 1}", headers: {'Content-Type': 'application/json; charset=UTF-8'}})
• params: shorthand for setting get params. expect an object with key/value pair. will convert it to querystring.
  • this: `ld$.fetch("url", {}, {params: {qs: "some text"}}
  • is the same with this: `ld$.fetch("url?qs=some%20text", {}, {})
• timeout: elapsed time ( in milliseconds ) for a timeout error to be fired. default 40s
• no-default-headers: default null. set this to true to bypass default headers in ld$.fetch.headers.

You can also config global headers by updating values in ld$.fetch.headers:

ld$.fetch.headers["X-CSRF-TOKEN"] = ...

XMLHttpRequest

While fetch is newer than XMLHttpRequest, for now XMLHttpRequest does better in handling progress information. Thus you can use ld$.xhr instead of ld$.fetch if such information is needed.

Using xhr is almost identical with using fetch:

ld$.xhr(<URL>, <RAWOPTION>, <LDQOPTION>)
  .then ->  ...
  .catch (e) -> # use e.data to get raw response from fetch

Yet it accepts one additional ldquery option:

• progress({percent, val, len}): a callback function accepting progress information as an object
  • percent: 0 ~ 1, 1 = finished.
  • val: current progress.
  • len: expected total progress.
  • this function has no expected return value.

Error Handling

ld$.fetch doesn't depend on ldError, but it indeed returns ldError compatible errors, with following fields:

• name: ldError
• id: error code
• code: http code. ( optional )
• data: returned data
• json: parsed json from returned data, if any ( optional )

When request failed, ld$.fetch will try to parse returned data as json, and check if there is a field "name" with value "ldError". If "ldError" name field exists, this object will be used directly to construct the Error object.

Compatibility

ldquery uses following modern web features:

• fetch api - not support in IE, Older Edge ( <= 13). Use polyfill to support to IE >= 11
• classList - not support well in IE. Use Polyfill to fix this.
• Array.from - not supported in IE. Use Polyfill to fix this.

License

MIT License.