salvager

salvager

Reuse row elements when displaying large datasets. This is beneficial to performance since the number of row elements rendered to the DOM is fixed, no matter how big the dataset is.

Caveats

• Assumes a consistent row height
• If data.length * rowHeight exceeds the maximum element height for a particular browser, all rows may not be displayed.

Installation

$ npm install salvager --save

You can also use the files in dist, where salvager is exposed via UMD.

Example

import salvager from 'salvager';

const data = [];
for (let i = 1; i <= 50000; i++) data.push('Item ' + i);

salvager({
  target: document.querySelector('.Container'),
  data: data,
  bufferSize: 50,
  buildRow(data) {
    var row = document.createElement('div');
    row.style.padding = '10px';
    row.textContent = data;
    row.style.backgroundColor = getStripeColour(data);
    return row;
  },
  updateRow(row, data) {
    row.textContent = data;
    row.style.backgroundColor = getStripeColour(data);
  }
});

function getStripeColour(data) {
  if (data.split(' ').pop() % 2 === 0) return '#eee';
  return '#fff';
}

To run the browser example:

$ npm run example

API

salvager(target, data, [bufferSize], [buildRow], [updateRow])

Renders recyclable rows based on data into the target element.

Arguments

• target - The element which will contain the recyclable row elements.
• data - The array of data to display.
• bufferSize - Optional The number of row elements rendered into the DOM, which will be recycled as the list is scrolled. Defaults to 100.
• buildRow - Optional The function used to generate each row element. Defaults to:

data => {
  const row = document.createElement('div');
  row.textContent = data;
  return row;
}

• updateRow - Optional The function used when updating a row element. Defaults to:

(row, data) => row.textContent = data

Tests

$ npm run test-local

React

Salvager has been ported to a React module, see react-salvager.

Credits

• The core algorithm is based on @cmpolis's Smart Table Scroll. I thought it was a great idea, so decided to dig into it some more and tweak it here :smile:
• @gaearon's Redux for ideas around webpack setup, npm run scripts, and dot files :+1:

License

MIT