lazy-instance
v1.0.1
Published
Lazily define instance properties through the prototype chain
Downloads
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Maintainers
whendersonReadme
lazy-instance
Lazily define instance properties through the prototype chain.
This provides a mechanism to dynamically add instance values via the prototype chain without modifying constructors. Very useful for those using a subscriber pattern such as AngularJs or KnockoutJs.
Installation
Node
npm install lazy-instanceWeb
bower install lazy-instanceUsage
node
var lazyInstance = require('lazy-instance');
function MyClass() {}
lazyInstance(MyClass, 'value', function () {
return 'lazy value';
});
console.log('result:', new MyClass().value);web (global)
<html>
<head>
<script type="text/javascript" src="lazy-instance.web.min.js"></script>
</head>
<body>
<script>
function MyClass() {}
lazyInstance(MyClass, 'value', function () {
return 'lazy value';
});
console.log('result:', new MyClass().value);
</script>
</body>
</html>web (amd)
require.config({
paths: {
"lazy-instance": "lazy-instance.web.min.js"
}
});
require(['lazy-instance'], function (lazyInstance) {
function MyClass() {}
lazyInstance(MyClass, 'value', function () {
return 'lazy value';
});
console.log('result:', new MyClass().value);
});API
lazyInstance(ctor, name, create)
Assigns a lazy instance property to the prototype chain of ctor.
Examples
KnockoutJS
function MyClass(a) {
this.a = ko.observable(a);
}
lazyInstance(MyClass, 'b', function () {
return ko.observable(2);
});
lazyInstance(MyClass, 'c', function () {
return ko.pureComputed(function () {
return this.a() + this.b();
}, this);
});
var instances = [
new MyClass(0),
new MyClass(1),
new MyClass(2)
];
console.log('result:', instances[0].c(), instances[1].c(), instances[2].c());
// result: 2 3 4
instances[0].a(3); instances[0].b(5); // 8
instances[1].a(7); instances[1].b(11); // 18
instances[2].a(13); instances[2].b(17); // 30
console.log('result:', instances[0].c(), instances[1].c(), instances[2].c());
// result: 8 18 30