// ==UserScript==
// @name         FunctionHooker.js
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Hook most functions on runtime via the function name
// @author       You
// @match        *://*.*
// @grant        none
// ==/UserScript==
class FunctionHooker {
constructor() {
this.hooks = new Map();
this.originalName = "";
}
getOriginal(functionName) {
return this.hooks.get(functionName);
}
hook(targetFunction, hookFunction) {
const isString = typeof targetFunction == "string";
// TODO: isString is used to eventually distinct a target function passed as a direct reference
// to a function from the user passing a function name as a string
// problem is there is no way to go from a function reference to a proper function name string
const isFullyQualifiedName = targetFunction.indexOf('.') != -1;
this.originalName = targetFunction;
if (isFullyQualifiedName) { this.hookFullyQualified(targetFunction, hookFunction); return; }
const originalFunction = window[targetFunction];
if (originalFunction) {
this.hooks.set(targetFunction, originalFunction);
window[targetFunction] = hookFunction;
} else {
throw new Error(`Function '${targetFunction}' does not exist in the 'window' object.`);
}
}
unhook(functionName) {
const isFullyQualifiedName = functionName.indexOf('.') != -1;
if (isFullyQualifiedName) { this.unhookFullyQualified(functionName); return; }
const originalFunction = this.hooks.get(functionName);
if (originalFunction) {
window[functionName] = originalFunction;
this.hooks.delete(functionName);
} else {
throw new Error(`Function '${functionName}' is not hooked.`);
}
}
resolveFullyQualifiedFunctionName(functionName) {
const functionNames = functionName.split('.');
let resolvedFunction = window;
for (const name of functionNames) {
resolvedFunction = resolvedFunction[name];
if (!resolvedFunction) {
throw new Error(`Function '${functionName}' does not exist.`);
}
}
return resolvedFunction;
}
hookFullyQualified(functionName, hookFunction) {
const resolvedFunction = this.resolveFullyQualifiedFunctionName(functionName);
const originalFunction = resolvedFunction;
this.hooks.set(functionName, originalFunction);
const parentObject = functionName
.split('.')
.slice(0, -1)
.reduce((obj, prop) => (obj[prop] ? obj[prop] : obj), window);
const functionNameLeaf = functionName.split('.').pop();
if (typeof parentObject[functionNameLeaf] != 'function') { debugger; throw new Error(`Function '${this.originalName}' is not hooked.`); }
parentObject[functionNameLeaf] = hookFunction;
}
unhookFullyQualified(functionName) {
const resolvedFunction = this.resolveFullyQualifiedFunctionName(functionName);
const originalFunction = this.hooks.get(functionName);
if (originalFunction) {
const parentObject = functionName
.split('.')
.slice(0, -1)
.reduce((obj, prop) => (obj[prop] ? obj[prop] : obj), window);
const functionNameLeaf = functionName.split('.').pop();
parentObject[functionNameLeaf] = originalFunction;
this.hooks.delete(functionName);
} else {
throw new Error(`Function '${functionName}' is not hooked.`);
}
}
}