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Hooks

A JavaScript hook/proxy/reflect ultility

Tính đến 12-04-2016. Xem phiên bản mới nhất.

Script này sẽ không được không được cài đặt trực tiếp. Nó là một thư viện cho các script khác để bao gồm các chỉ thị meta // @require https://update.greasyfork.org/scripts/18715/119137/Hooks.js 

// ==UserScript==
// @name			Hooks
// @namespace		[email protected]
// @description		A JavaScript hook/proxy/reflect ultility
// @author			xymopen
// @version			1.1.0
// @grant			none
// @license			BSD 2-Clause
// @homepageURL		https://github.com/xymopen/JS_Utilities/blob/master/Hooks.js
// @updateURL		https://raw.githubusercontent.com/xymopen/JS_Utilities/master/Hooks.js
// ==/UserScript==

// TODO: JsDoc

var Hooks = ( function() {
    "use strict";

	var Hooks = {
        "apply": function apply( target, onApply ) {
			return function() {
                return onApply.call( this, target, this, arguments );
            };
        },

        "property": function get( target, propertyName, onGet, onSet ) {
            var descriptor, oldValue;

            if ( Object.prototype.hasOwnProperty.call( target, propertyName ) ) {
                descriptor = Object.getOwnPropertyDescriptor( target, propertyName );

                if ( Object.prototype.hasOwnProperty.call( descriptor, "value" ) ) {
                    oldValue = descriptor.value;

                    delete descriptor.value;
                    delete descriptor.writable;
                } else if ( Object.prototype.hasOwnProperty.call( descriptor, "get" ) ) {
                    oldValue = descriptor.get.call( target );
                } else {
                    oldValue = undefined;
                }

                descriptor.get = function get() {
                    return onGet.call( this, target, propertyName, oldValue );
                };

                descriptor.set = function set( newValue ) {
                    oldValue = onSet.call( this, target, propertyName, oldValue, newValue );
                    return oldValue;
                };

                Object.defineProperty( target, propertyName, descriptor );
            } else {
                throw new Error( "ERR_PROPERTY_NOT_DEFINED" );
            }
        },

        "get": function get( target, propertyName, onGet ) {
            return Hooks.property( target, propertyName, onGet, function( target, propertyName, oldValue, newValue ) {
                return newValue;
            } );
        },

        "set": function set( target, propertyName, onSet ) {
            return Hooks.property( target, propertyName, function( target, propertyName, oldValue ) {
                return oldValue;
            }, onSet );
        },

        "getter": function getter( target, propertyName, onGetter ) {
            var descriptor, getter;

            if ( Object.prototype.hasOwnProperty.call( target, propertyName ) ) {
                descriptor = Object.getOwnPropertyDescriptor( target, propertyName );
                getter = descriptor.get;

                if ( Object.prototype.hasOwnProperty.call( descriptor, "get" ) &&
                    "function" === typeof getter ) {
                    descriptor.get = Hooks.apply( getter, function( getter, thisArg, argv ) {
                        return onGetter.call( this, target, propertyName, getter, thisArg, argv );
                    } );
                } else {
                    throw new Error( "ERR_NOT_A_GETTER" );
                }

                Object.defineProperty( target, propertyName, descriptor );
            } else {
                throw new Error( "ERR_PROPERTY_NOT_DEFINED" );
            }
        },

        "setter": function setter( target, propertyName, onSetter ) {
            var descriptor, setter;	// variable setter refers to setter( target, propertyName, onSetter ) itself

            if ( Object.prototype.hasOwnProperty.call( target, propertyName ) ) {
                descriptor = Object.getOwnPropertyDescriptor( target, propertyName );
                setter = descriptor.set;

                if ( Object.prototype.hasOwnProperty.call( descriptor, "set" ) &&
                    "function" === typeof setter ) {
                    descriptor.set = Hooks.apply( setter, function( setter, thisArg, argv ) {
                        return onSetter.call( this, target, propertyName, setter, thisArg, argv );
                    } );
                } else {
                    throw new Error( "ERR_NOT_A_SETTER" );
                }

                Object.defineProperty( target, propertyName, descriptor );
            } else {
                throw new Error( "ERR_PROPERTY_NOT_DEFINED" );
            }
        },

        "method": function method( target, methodName, onApply ) {
            var method;

            if ( Object.prototype.hasOwnProperty.call( target, methodName ) ) {
                method = target[ methodName ];

                if ( "function" === typeof method ) {
                    target[ methodName ] = Hooks.apply( method, function( method, thisArg, argv ) {
                        return onApply.call( this, target, methodName, method, thisArg, argv );
                    } );
                } else {
                    throw new Error( "ERR_NOT_A_METHOD" );
                }
            } else {
                throw new Error( "ERR_PROPERTY_NOT_DEFINED" );
            }
        }
    };

    return Hooks;
} )();