单例模式: 保证一个类仅有一个实例,并提供一个访问它的全局访问点html
使用 CreateDiv 单例类,它的做用是负责在页 面中建立惟一的 div 节点设计模式
var CreateDiv = function( html ){
this.html = html;
this.init();
};
CreateDiv.prototype.init = function(){
var div = document.createElement( 'div' );
div.innerHTML = this.html;
document.body.appendChild( div );
};
var ProxySingletonCreateDiv = (function(){
var instance;
return function( html ){
if ( !instance ){
instance = new CreateDiv( html );
}
return instance;
}
})();
var a = new ProxySingletonCreateDiv( 'sven1' );
var b = new ProxySingletonCreateDiv( 'sven2' );
alert( a === b ); //true
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指的是在须要的时候才建立对象实例。惰性单例是单例模式的重点bash
建立惟一的浮窗app
var getSingle = function( fn ){
var result;
return function(){
return result || ( result = fn .apply(this, arguments ) );
}
};
var createLoginLayer = function(){
var div = document.createElement( 'div' );
div.innerHTML = '我是登陆浮窗';
div.style.display = 'none';
document.body.appendChild( div );
return div;
};
var createSingleLoginLayer = getSingle( createLoginLayer );
document.getElementById( 'loginBtn' ).onclick = function(){
var loginLayer = createSingleLoginLayer();
loginLayer.style.display = 'block';
};
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