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User Guide

All information for developers using vapjs-filter should consult this document.

Install

npm install --save vapjs-filter

Usage

const HttpProvider = require('vapjs-provider-http');
const Vap = require('vapjs-query');
const VapFilter = require('vapjs-filter');
const vap = new Vap(new HttpProvider('http://localhost:8545'));
const filters = new VapFilter(vap);


const filter = new filters.Filter({ delay: 300 })
.new({ toBlock: 500 })
.then((result) => {
  // result <BigNumber ...> filterId
})
.catch((error) => {
  // result null
});
filter.watch((result) => {
  // result [{...}, ...] (fires multiple times)
});
filter.uninstall(cb);


const filter = new filters.BlockFilter()
.at(7)
filter.watch((result) => {
  // result [{...}, ...] (fires multiple times)
});
filter.uninstall(cb);


const filter = new filters.PendingTransactionFilter()
.new()
.then((result) => {
  // result <BigNumber ...> filterId
})
.catch((error) => {
  // result null
});

const watcher = filter.watch((error, result) => {
  // result null ['0xfd234829...', '0xsf2030d1...']
});
watcher.stopWatching(cb);

filter.uninstall()
.then((result) => {
  // result true
})
.catch((error) => {
  // result null
});

Available Filters

There are three kinds of available filters Filter, BlockFilter and PendingTransactionFilter.

Polling

Each filter object starts a single interval to poll for new changes on the filter. Multiple watchers can be installed to poll for changes. The delay of the interval polling can be set in the Filter constructor (i.e. new filters.Filter({ delay: 400 })). The delay option is in milliseconds.

Using the .new method

The filter .new method will install the filter on the Vapory node. This is where you can specify the vap_newFilter param object (i.e. { toBlock: 5, fromBlock: 'latest' } etc.).

Using the .at method

If you have a filter already installed at a specific filter ID. You can setup another filter instance at that filter id, by using the .at method (i.e. filter.at(filterId)). The filter id can be specified as a type Number, number as a String or BigNumber Instance.

Uninstalling

Uninstalling the filter will clear the filter interval and uninstall the fitler from the node.

Browser Builds

vapjs provides production distributions for all of its modules that are ready for use in the browser right away. Simply include either dist/vapjs-filter.js or dist/vapjs-filter.min.js directly into an HTML file to start using this module. Note, an VapFilter object is made available globally.

<script type="text/javascript" src="vapjs-filter.min.js"></script>
<script type="text/javascript">
var filter = new VapFilter(...);
</script>

Note, even though vapjs should have transformed and polyfilled most of the requirements to run this module across most modern browsers. You may want to look at an additional polyfill for extra support.

Use a polyfill service such as Polyfill.io to ensure complete cross-browser support: https://polyfill.io/

Other Awesome Modules, Tools and Frameworks

  • web3.js -- the original Vapory swiss army knife Vapory Foundation
  • vaporyjs -- critical vaporyjs infrastructure Vapory Foundation
  • browser-solidity -- an in browser Solidity IDE Vapory Foundation
  • wafr -- a super simple Solidity testing framework
  • truffle -- a solidity/js dApp framework
  • embark -- a solidity/js dApp framework
  • dapple -- a solidity dApp framework
  • chaitherium -- a JS web3 unit testing framework
  • contest -- a JS testing framework for contracts

Our Relationship with Vapory & VaporyJS

We would like to mention that we are not in any way affiliated with the Vapory Foundation or vaporyjs. However, we love the work they do and work with them often to make Vapory great! Our aim is to support the Vapory ecosystem with a policy of diversity, modularity, simplicity, transparency, clarity, optimization and extensibility.

Many of our modules use code from web3.js and the vaporyjs- repositories. We thank the authors where we can in the relevant repositories. We use their code carefully, and make sure all test coverage is ported over and where possible, expanded on.