Knockout.js修改ko.observable（）之前的值写入

Question

我有一个包含大量变量的工作视图模型。

我在文本框中使用autoNumeric（http://www.decorplanit.com/plugin/）进行文本格式设置。我想在计算的可观察值中使用输入字段的观察数据，但如果格式化的可观察文本字段被修改，格式也会保存在变量中。

我怎样才能只观察没有格式化输入字段的值？

我认为这最好的方法可能是一个getter/setter到observable，并在设置值时删除格式。我找不到在knockout的文档中为ko.observable（）编写get/set方法的解决方案，而ko.computed（）不能存储值。

我不想使用隐藏字段或额外的变量。
没有它，这可能吗？

Answer 1

解决方案，在http://knockoutjs.com/documentation/extenders.html

ko.extenders.numeric = function(target, precision) { 
//create a writeable computed observable to intercept writes to our observable 
var result = ko.computed({ 
    read: target, //always return the original observables value 
    write: function(newValue) { 
     var current = target(), 
      roundingMultiplier = Math.pow(10, precision), 
      newValueAsNum = isNaN(newValue) ? 0 : parseFloat(+newValue), 
      valueToWrite = Math.round(newValueAsNum * roundingMultiplier)/roundingMultiplier; 

     //only write if it changed 
     if (valueToWrite !== current) { 
      target(valueToWrite); 
     } else { 
      //if the rounded value is the same, but a different value was written, force a notification for the current field 
      if (newValue !== current) { 
       target.notifySubscribers(valueToWrite); 
      } 
     } 
    } 
}); 

//initialize with current value to make sure it is rounded appropriately 
result(target()); 

//return the new computed observable 
return result; 
}; 

所看到后来就

function AppViewModel(one, two) { 
    this.myNumberOne = ko.observable(one).extend({ numeric: 0 }); 
    this.myNumberTwo = ko.observable(two).extend({ numeric: 2 }); 
} 

Answer 2

您可以使用ko.computed（）。你可以指定一个写选项，看到Writeable computed observables

例（从淘汰赛资料为准）：

function MyViewModel() { 
    this.price = ko.observable(25.99); 

    this.formattedPrice = ko.computed({ 
     read: function() { 
      return '$' + this.price().toFixed(2); 
     }, 
     write: function (value) { 
      // Strip out unwanted characters, parse as float, then write the raw data back to the underlying "price" observable 
      value = parseFloat(value.replace(/[^\.\d]/g, "")); 
      this.price(isNaN(value) ? 0 : value); // Write to underlying storage 
     }, 
     owner: this 
    }); 
} 

ko.applyBindings(new MyViewModel());