简单的js框架，DOM。 （模块式的，如jQuery）问题与添加方法

Question

的任务是在jQuery的风格编写简单的框架，来解决这个我已经写代码：

(function(window) { 
window.smp=function smpSelector(selector) { 
    return new smpObj(selector); 
    } 

function smpObj(selector) { 
    this.length = 0; 
    if (!selector) { 
     this.el = []; 
     return this; 
     } 
    if(typeof selector == 'string'){ 
     if(selector[0]==='#'){ 
      this.el = [document.getElementById(selector.slice(1, selector.length))]; 
      this.length = 1; 
      return this; 
     } else if(selector[0]==='.'){ 
      this.el = document.getElementsByClassName(selector.slice(1, selector.length)); 
      this.length = this.el.length; 
      return this; 
     } else { 
      this.el = document.getElementsByTagName(selector); 
      this.length = this.el.length; 
      return this; 
     } 
    } 
    else return null;   
} 
window.smp.changeColor=function smpColor(color) { 
    for (var i = 0; i < this.length; i++) 
      this.el[i].style.color = color; 
    } 
})(window); 

，它的工作确定。我可以打电话给这样的：

smp('div') 

但后来我试着添加方法：

window.smp.changeColor=function smpColor(color) { 
    for (var i = 0; i < this.length; i++) 
      this.el[i].style.color = color; 
    } 

而且它不能正常工作。

smp('div').changeColor('color') 

（不能这样调用）
我会很感激，如果有人能告诉我的错误。
我用这篇文章article

Answer 1

既然你return this在smpObj功能，this是smpObj不window.smp的实例，有一个为smpObj没有changeColor方法。

要使其工作，你可以这样做：

(function(window) { 
    window.smp = function smpSelector(selector) { 
    return new smpObj(selector); 
    }; 

    function smpObj(selector) { 
    this.length = 0; 
    this.changeColor = function smpColor(color) { 
     for (var i = 0; i < this.length; i++) this.el[i].style.color = color; 
    }; 
    if (!selector) { 
     this.el = []; 
     return this; 
    } 
    if (typeof selector == "string") { 
     if (selector[0] === "#") { 
     this.el = document.getElementById(selector.slice(1, selector.length)); 
     this.length = 1; 
     return this; 
     } else if (selector[0] === ".") { 
     this.el = document.getElementsByClassName(
      selector.slice(1, selector.length) 
     ); 
     this.length = this.el.length; 
     return this; 
     } else { 
     this.el = document.getElementsByTagName(selector); 
     this.length = this.el.length; 
     return this; 
     } 
    } else return null; 
    } 
})(window); 

然后尝试

smp('div').changeColor('red')