javascript NodeJS 模块导出/原型 - 没有方法
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NodeJS Module exports / prototype - has no method
提问by Alex
I've got a module that looks like this:
我有一个看起来像这样的模块：
var MyModule = module.exports = function MyModule(opts) {
opts = (opts === Object(opts)) ? opts : {};
if (!(this instanceof MyModule)) {
return new MyModule(opts);
}
for (var key in opts) if ({}.hasOwnProperty.call(opts, key)) {
this.config[key] == opts[key];
}
};
MyModule.prototype.config = {
something:'value'
}
MyModule.prototype.put = function put(info, cb) {
//do stuff
};
However, when I use it like this:
但是，当我像这样使用它时：
var myModule = require('myModule.js');
myModule.put({test}, function(){
//some callback stuff
});
I get the following error:
我收到以下错误：
TypeError: Object function MyModule(opts) {
opts = (opts === Object(opts)) ? opts : {}; if (!(this instanceof MyModule)) { return new MyModule(opts); } for (var key in opts) if ({}.hasOwnProperty.call(opts, key)) { this.config[key] == opts[key]; } } has no method 'put'
类型错误：对象函数 MyModule(opts) {
opts = (opts === Object(opts)) ? opts : {}; if (!(this instanceof MyModule)) { return new MyModule(opts); } for (var key in opts) if ({}.hasOwnProperty.call(opts, key)) { this.config[key] == opts[key]; } } has no method 'put'
It appears I have something wrong with my MyModule.prototype.put?
看来我的MyModule.prototype.put?
回答by kevin
You wrote :
你写了 ：
var myModule = require('myModule.js');
myModule.put({}, function(){
//some callback stuff
});
Here myModuleis in fact MyModule, a constructor function. So what you are doing is MyModule.put(), a call to a "static" method of MyModule. MyModule.prototype.putdefines an "instance" method so you have to instanciate first :
这里myModule实际上是MyModule一个构造函数。所以你正在做的是MyModule.put()，调用MyModule. MyModule.prototype.put定义了一个“实例”方法，所以你必须先实例化：
var MyModule = require('./myModule.js');
var myModule = new MyModule();
// or as you used `if (!(this instanceof MyModule)) { … }`
var myModule = MyModule();
myModule.put({}, function () {});
So basically your code needs just a pair of ()to work :
所以基本上你的代码只需要一对就()可以工作：
MyModule().put({}, function () {});
// same as
(new MyModule).put({}, function () {});
Récap :
回顾：
var MyModule = function () {
// Construct object
};
MyModule.staticMethod = function () {
this; // is bound to `MyModule` function object
};
MyModule.prototype.instanceMethod = function () {
this; // is bound to the `MyModule` instance object it's called from
};
// Usage
MyModule.staticMethod();
var instance = new MyModule();
instance.instanceMethod();
回答by Sly_cardinal
With this code var myModule = require('myModule.js');your myModulevariable looks like a constructor function, not an instance of myModule.
使用此代码，var myModule = require('myModule.js');您的myModule变量看起来像一个构造函数，而不是 myModule 的实例。
Try instantiating your module first:
首先尝试实例化您的模块：
var MyModule = require('myModule.js');
var myModule = new MyModule(); // Create an instance of your module.
// Now use it.
myModule.put(/*... your code here ...*/);
