javascript - 如何使用call或Apply调用javascript构造函数？ [复制]

This question already has answers here:

Use of .apply() with 'new' operator. Is this possible?

(36个答案)


5年前关闭。




如何将下面的函数归纳为N个参数？ (使用电话还是申请？)

是否有编程方式将参数应用于"new"？我不希望将构造函数视为普通函数。

/**
 * This higher level function takes a constructor and arguments
 * and returns a function, which when called will return the
 * lazily constructed value.
 *
 * All the arguments, except the first are pased to the constructor.
 *
 * @param {Function} constructor
 */

function conthunktor(Constructor) {
    var args = Array.prototype.slice.call(arguments, 1);
    return function() {
        console.log(args);
        if (args.length === 0) {
            return new Constructor();
        }
        if (args.length === 1) {
            return new Constructor(args[0]);
        }
        if (args.length === 2) {
            return new Constructor(args[0], args[1]);
        }
        if (args.length === 3) {
            return new Constructor(args[0], args[1], args[2]);
        }
        throw("too many arguments");
    }
}

q单元测试:

test("conthunktorTest", function() {
    function MyConstructor(arg0, arg1) {
        this.arg0 = arg0;
        this.arg1 = arg1;
    }
    MyConstructor.prototype.toString = function() {
        return this.arg0 + " " + this.arg1;
    }

    var thunk = conthunktor(MyConstructor, "hello", "world");
    var my_object = thunk();
    deepEqual(my_object.toString(), "hello world");
});

最佳答案

试试这个:

function conthunktor(Constructor) {
    var args = Array.prototype.slice.call(arguments, 1);
    return function() {

         var Temp = function(){}, // temporary constructor
             inst, ret; // other vars

         // Give the Temp constructor the Constructor's prototype
         Temp.prototype = Constructor.prototype;

         // Create a new instance
         inst = new Temp;

         // Call the original Constructor with the temp
         // instance as its context (i.e. its 'this' value)
         ret = Constructor.apply(inst, args);

         // If an object has been returned then return it otherwise
         // return the original instance.
         // (consistent with behaviour of the new operator)
         return Object(ret) === ret ? ret : inst;

    }
}

关于javascript - 如何使用call或Apply调用javascript构造函数？ [复制]，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/3362471/