index.js

import {hasOwnProperty} from '../utils';
// decorator the same as wrapper
// the same as aop
// cannot assure object's all functions

// can change args or compare beforeFn, afterFn and selfFn
// Function.prototype.beforeFn = function(beforeFn) {
//     let selfFn = this;
//     return function(...args) {
//         beforeFn.apply(this, args);
//         return selfFn.apply(this, args);
//     }
// }

// Function.prototype.afterFn = function (afterFn) {
//     let selfFn = this;
//     return function (...args) {
//         let ret = selfFn.apply(this, args);
//         afterFn.apply(this, args);
//         return ret;
//     }
// }

// but how to operation new action ?
// fn's static method cannot to invoke;

export const beforeFunction = function (fn, beforeFn, compareFn) {
    let f =  function(...args) {
        if (typeof compareFn === 'function' && beforeFn.apply(this, args) !== compareFn.apply(this, args))
            // fire fn?
            return;
        if (typeof compareFn !== 'function')
            beforeFn.apply(this, args);
        
        return fn.apply(this, args);
    };
    for(let prop in fn) {
        if(hasOwnProperty(fn, prop)) {
            f[prop] = fn[prop];
        }
    }
    return f;
}

export const afterFunction = function (fn, afterFn, compareFn) {
    let f = function(...args) {
        let ret = fn.apply(this, args);
        if (typeof compareFn === 'function' && ret !== compareFn.apply(this, args))
            return ret;
        afterFn.apply(this, args);
        return ret;
    }
    for(let prop in fn) {
        if(hasOwnProperty(fn, prop)) {
            f[prop] = fn[prop];
        }
    }
    return f;
}