phosphor-observablelist

A sequence container which can be observed for changes.

API Docs

Package Install

Prerequisites

• node

npm install --save phosphor-observablelist

Source Build

Prerequisites

• git
• node

git clone https://github.com/phosphorjs/phosphor-observablelist.git
cd phosphor-observablelist
npm install

Rebuild

npm run clean
npm run build

Run Tests

Follow the source build instructions first.

npm test

Build Docs

Follow the source build instructions first.

npm run docs

Navigate to docs/index.html.

Supported Runtimes

The runtime versions which are currently known to work are listed below. Earlier versions may also work, but come with no guarantees.

• Node 0.12.7+
• IE 11+
• Firefox 32+
• Chrome 38+

Bundle for the Browser

Follow the package install instructions first.

npm install --save-dev browserify
browserify myapp.js -o mybundle.js

Usage Examples

Note: This module is fully compatible with Node/Babel/ES6/ES5. Simply omit the type declarations when using a language other than TypeScript.

To observe changes to the list, simply hook a callable up to the changed signal:

let called = false;
let list = new ObservableList<number>();
list.changed.connect(() => { called = true; });

// Insert `1` at index `0`
list.insert(0, 1); // called === true;

console.log(list); // [1]
list.clear();
console.log(list); // []

for more advanced behaviour, use the args passed by default to the callable:

let list = new ObservableList<number>();
list.changed.connect((sender, args) => {
  console.log(args.type); // ListChangeType.Add
  console.log(args.newIndex); // 0
  console.log(args.newValue); // 1
  console.log(args.oldIndex); // -1
  console.log(args.oldValue); // void 0
});
list.add(1); // will give the change args above.

Default arguments can be passed into the constructor:

let list = new ObservableList<number>([1, 1, 2, 3, 5, 8]);
// or
let strlist = new ObservableList<string>(['f', 'i', 'b']);

Retrieve an item at a given index in the list using .get:

let list = new ObservableList<number>([1, 1, 2, 3, 5, 8]);
list.get(4); // 5

// this will offset from the end of the list if passed
// a negative index
list.get(-2); // 5

// and will return `undefined` if the index is out of range
list.get(101); // void 0

indexOf works just like arrays in javascript/typescript:

let list = new ObservableList<number>([1, 2, 3, 1, 2, 3]);
list.indexOf(2); // 1 - returns the first occurrence.
list.indexOf(4); // -1

contains returns a boolean to denote whether the item was found:

let list = new ObservableList<string>(['a', 'b', 'c']);
list.contains('a'); // true
list.contains('d'); // false

ObservableList also has slice behaviour:

let list = new ObservableList<number>([1, 2, 3]);
list.slice(); // [1, 2, 3] - this returns a copy
list.slice(1); // 2
list.slice(-1); // 3
list.slice(4); // []
list.slice(1, -1); // 2

To set an item at a given index, use set. This returns the item which previously occupied that index:

let list = new ObservableList<number>([1, 2, 3, 4]);
list.set(1, 5); // returns 2
console.log(list); // [1, 5, 3, 4]
list.set(-1, 8); // returns 4
console.log(list); // [1, 5, 3, 8]

To replace all the items in a list, use assign. This also returns the previous items:

let list = new ObservableList<string>(['a', 'b', 'c']);
list.assign(['f']); // returns ['a', 'b', 'c']
console.log(list); // 'f'

To add items to the list, use add:

let list = new ObservableList<number>([1, 2, 3]);
list.add(4); // returns 3, the index of the new item.
console.log(list); // [1, 2, 3, 4]

To move items internally, use move:

let list = new ObservableList<number>([1, 2, 3]);

// move item at index `1` to index `2`
list.move(1, 2); // true
console.log(list); // [1, 3, 2]

To remove an item from the list, use remove. This will remove the first occurrence of the item:

let list = new ObservableList<number>([1, 2, 3, 1]);
list.remove(1); // returns 0
console.log(list); [2, 3, 1]

To remove an item at a specific index, use removeAt:

let list = new ObservableList<number>([1, 2, 3]);
list.removeAt(1); // 2
console.log(list); // [1, 3]