Javascript中的纪念品

Question

我正在寻找在CRUD表单中使用的memento模式(GoF)的JavaScript实现.在基本级别上,撤消对输入的更改就足够了,但将它与标准JS框架(如YUI或Ext)一起使用来撤消和重做网格操作(新行,删除行等)会很棒.

谢谢

Answer 1

因为我没有看到任何代码示例,所以这里是一个快速'n脏实现撤消EXT表单:

var FormChangeHistory = function(){
    this.commands = [];
    this.index=-1;
}

FormChangeHistory.prototype.add = function(field, newValue, oldValue){
    //remove after current 
    if (this.index > -1 ) {
        this.commands = this.commands.slice(0,this.index+1)
    } else {
        this.commands = []
    }
    //add the new command
    this.commands.push({
        field:field,
        before:oldValue,
        after:newValue
    })
    ++this.index
}

FormChangeHistory.prototype.undo = function(){
    if (this.index == -1) return;
    var c = this.commands[this.index];
    c.field.setValue(c.before);
    --this.index
}

FormChangeHistory.prototype.redo = function(){
    if (this.index +1 == this.commands.length) return;
    ++this.index
    var c = this.commands[this.index];
    c.field.setValue(c.after);
}

Ext.onReady(function(){
    new Ext.Viewport({
        layout:"fit",
        items:[{    
            xtype:"form",
            id:"test_form",
            frame:true,
            changeHistory:new FormChangeHistory("test_form"),
            defaults:{
                listeners:{
                    change:function( field, newValue, oldValue){
                        var form = Ext.getCmp("test_form")
                        form.changeHistory.add(field, newValue, oldValue)
                    }   
                }
            },
            items:[{
                fieldLabel:"type some stuff",
                xtype:"textfield"
            },{
                fieldLabel:"then click in here",
                xtype:"textfield"
            }],
            buttons:[{
                text:"Undo",
                handler:function(){
                    var form = Ext.getCmp("test_form")
                    form.changeHistory.undo();
                }
            },{
                text:"Redo",
                handler:function(){
                    var form = Ext.getCmp("test_form")
                    form.changeHistory.redo();
                }
            }]
        }]
    })
});

为可编辑网格实现这一点有点棘手,但是您应该能够创建一个GridChangeHistory来执行相同的操作,然后从EditorGrid的AfterEdit侦听器调用add()函数.

"之前"和"之后"属性可以是回调函数,允许您撤消/重做任何类型的命令,但在调用add()时需要更多工作