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A JavaScript hook/reply ultility
As of
This script should not be not be installed directly. It is a library for other scripts to include with the meta directive // @require https://update.greatest.deepsurf.us/scripts/18715/603567/Hooks.js
// ==UserScript== // @name Hooks // @namespace [email protected] // @description A JavaScript hook/reply ultility // @author xymopen // @version 1.1.3 // @grant none // @license BSD 2-Clause // @homepageURL https://github.com/xymopen/JS_Misc/blob/master/Hooks.js // @updateURL https://raw.githubusercontent.com/xymopen/JS_Misc/master/Hooks.js // ==/UserScript== // TODO: JsDoc // TODO: Unit test var Hooks = ( function() { "use strict"; /** * Hooks functions or properties, getters/setters * and methods of an object you are intrested in */ var Hooks = { /** * hook a function * @function apply * @param {function} target - a function to be hook * @param {onApply} onApply - the hook */ "apply": function apply( target, onApply ) { if ( "function" === typeof target && "function" === typeof onApply ) { return function() { return onApply.call( this, target, this, arguments ); }; } else { throw new TypeError(); } }, /** * @callback onApply the hook * @param {function} target - the function hooked * @param {object|undefined} thisArg - #this reference * @param {arguments} argv - the arguments pass to the target */ /** * hook a property of an object * @function property * @param {object} target - an object having or to have the property to be hooked * @param {string} propertyName - the name of the property to be hooked * @param {onGet} onGet - the hook call when about to get the property * @param {onSet} onSet - the hook call when about to set the property */ "property": function property( 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; } } else { descriptor = { "configurable": true, "enumerable": true, }; 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 ); }, /** * the hook call when about to get the property * @callback onGet * @param {object} target - the object having the property hooked * @param {string} propertyName - the name of the property hooked * @param {any} oldValue - the current value of the property */ /** * the hook call when about to set the property * @callback onSet * @param {object} target - the object having the property hooked * @param {string} propertyName - the name of the property hooked * @param {any} oldValue - the current value of the property * @param {any} newValue - the value about to be set to the property */ /** * alias of #property but fill the #onSet automatically * @function get * @param {object} target - an object having or to have the property to be hooked * @param {string} propertyName - he name of the property to be hooked * @param {onGet} onGet - the hook call when about to get the property */ "get": function get( target, propertyName, onGet ) { return Hooks.property( target, propertyName, onGet, function( target, propertyName, oldValue, newValue ) { return Hooks.Reply.get( arguments ); } ); }, /** * the hook call when about to get the property * @callback onGet * @param {object} target - the object having the property hooked * @param {string} propertyName - the name of the property hooked * @param {any} oldValue - the current value of the property */ /** * alias of #property but fill the #onGet automatically * @function set * @param {object} target - an object having or to have the property to be hooked * @param {string} propertyName - the name of the property to be hooked * @param {onSet} onSet - the hook call when about to set the property */ "set": function set( target, propertyName, onSet ) { return Hooks.property( target, propertyName, function( target, propertyName, oldValue ) { return Hooks.Reply.set( arguments ); }, onSet ); }, /** * the hook call when about to set the property * @callback onSet * @param {object} target - the object having the property hooked * @param {string} propertyName - he name of the property hooked * @param {any} oldValue - the current value of the property * @param {any} newValue - the value about to be set to the property */ /** * hook a method of an object * @function method * @param {object} target - an object having or to have the method to be hooked * @param {string} methodName - the name of the method to be hooked * @param {onApply} onApply - the hook replace the method */ "method": function method( target, methodName, onApply ) { var method = target[ methodName ], descriptor; function hookMethod( method, onApply ) { return Hooks.apply( method, function( method, thisArg, argv ) { return onApply.call( this, target, methodName, method, thisArg, argv ); } ); }; if ( "function" === typeof method ) { target[ methodName ] = hookMethod( method, onApply ); } else { if ( Object.prototype.hasOwnProperty.call( target, propertyName ) ) { throw new Error( "ERR_PROPERTY_EXISTS_NOT_METHOD" ); } else { Hooks.set( target, methodName, function onSet( target, propertyName, oldValue, newValue ) { Object.defineProperty( target, methodName, { "configurable": true, "enumerable": true, "value": "function" === typeof newValue ? hookMethod( newValue, onApply ) : newValue, "writable": true, } ); } ); } } }, /** * the hook replace the method * @callback onApply * @param {object} target - the object having the method hooked * @param {string} methodName - the name of the method hooked * @param {object|undefined} thisArg - #this reference * @param {arguments} argv - the arguments pass to the method */ /** * hook a getter property of an object * @function getter * @param {object} target - an object having the getter property to be hooked * @param {string} propertyName - the name of the getter property to be hooked * @param {onGetter} onGetter - the hook replace the getter */ "getter": function getter( target, propertyName, onGetter ) { return trap( target, propertyName, onGetter, "get", "ERR_NOT_A_GETTER" ); }, /** * the hook replace the getter * @callback onSetter * @param {object} target - the object having the getter property hooked * @param {string} propertyName - he name of the getter property hooked * @param {function} getter - the getter replaced * @param {object|undefined} thisArg - #this reference * @param {arguments} argv - the arguments pass to the getter, should be #undefined */ /** * hook a setter property of an object * @function setter * @param {object} target - an object having the setter property to be hooked * @param {string} propertyName - the name of the setter property to be hooked * @param {onSetter} onSetter - the hook replace the setter */ "setter": function setter( target, propertyName, onSetter ) { return trap( target, propertyName, onSetter, "set", "ERR_NOT_A_SETTER" ); }, /** * the hook replace the setter * @callback onSetter * @param {object} target - the object having the setter property hooked * @param {string} propertyName - he name of the setter property hooked * @param {function} setter - the setter replaced * @param {object|undefined} thisArg - #this reference * @param {arguments} argv - the arguments pass to the setter, should be a right value */ }; var Reply = { "apply": function apply( param ) { var target = param[ 0 ], thisArg = param[ 1 ], argv = param[ 2 ]; return target.apply( thisArg, argv ); }, "get": function( param ) { var target = param[ 0 ], propertyName = param[ 1 ], oldValue = param[ 2 ], newValue = param[ 3 ]; return param[ param.length - 1 ]; }, "getter": function( param ) { var target = param[ 0 ], propertyName = param[ 1 ], fn = param[ 2 ], thisArg = param[ 3 ], argv = param[ 4 ]; return fn.apply( thisArg, argv ); }, "method": function method( param ) { var target = param[ 0 ], methodName = param[ 1 ], method = param[ 2 ], thisArg = param[ 3 ], argv = param[ 4 ]; return method.apply( thisArg, argv ); }, }; Reply.set = Reply.get; Reply.setter = Reply.getter; Hooks.Reply = Reply; return Hooks; } )();
