42 lines
1.2 KiB
JavaScript
42 lines
1.2 KiB
JavaScript
const _ = require('lodash');
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// Uses a hash of prototype properties and class properties to be extended.
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module.exports = function extend(protoProps, staticProps) {
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const Parent = this;
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// The constructor function for the new subclass is either defined by you
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// (the "constructor" property in your `extend` definition), or defaulted
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// by us to simply call the parent's constructor.
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const Child =
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protoProps && protoProps.hasOwnProperty('constructor')
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? protoProps.constructor
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: function() {
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return Parent.apply(this, arguments);
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};
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Object.assign(Child, Parent, staticProps);
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// Set the prototype chain to inherit from `Parent`.
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Child.prototype = Object.create(Parent.prototype, {
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constructor: {
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value: Child,
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enumerable: false,
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writable: true,
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configurable: true
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}
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});
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if (protoProps) {
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Object.assign(Child.prototype, protoProps);
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}
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// Give child access to the parent prototype as part of "super"
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Child.__super__ = Parent.prototype;
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// If there is an "extended" function set on the parent,
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// call it with the extended child object.
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if (_.isFunction(Parent.extended)) Parent.extended(Child);
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return Child;
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};
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