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/ldQuery@v1.0.0/dist/ldq.js
https://cdn.jsdelivr.net/gh/loadingio/ldQuery@v1.0.0/dist/ldq.min.js

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

<script src="https://cdn.jsdelivr.net/gh/loadingio/ldQuery@v1.0.0/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.

invoke these functions with ld$, e.g.,

ld$.find(document.body, '.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.
• 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.