Question

我有以下的淘汰代码来实现以下角色：

field1 + field2 -field3 = field4

$(function () {
ko.applyBindings(new AppViewModel());
});

function AppViewModel() {
this.original = ko.observable(0);
this.improvements = ko.observable(0);
this.depreciation = ko.observable(0);

this.total= ko.computed(function () {
    var total= 0;
    total= this.original() + this.improvements() - this.depreciation();
    return total;
}, this);
}

但由于某种原因，它无法正常工作，this.original总是乘以10。

例如：

1 + 1 - 1 = 10

知道是什么原因引起的吗？

这是我的HTML：

<div class="calc-form">
     <label>Original Purchase Price</label>
     <input type="text" id="original" data-bind="value: original" />

     <label>+ Improvements</label>
     <input type="text" id="improvements" data-bind="value: improvements" />

     <label>- Depreciation</label>
     <input type="text" id="depreciation" data-bind="value: depreciation" />

     <input type="button" class="calcbutton" value="Calculate" />
     <input type="button" class="calcbuttonreset" value="reset" />
     <p>= Total</p>
     <span data-bind="text: total"></span>
</div>

Answer 1

请注意，bool checkParticlesEmitted(ParticleSystem system) { ParticleSystem.Particle[] m_Particles = new ParticleSystem.Particle[system.particleCount]; int NumParticles = system.GetParticles(m_Particles); if (NumParticles > 0) { return true; } return false; }元素的值始终为字符串。 input "1" + "1" - "1"为"11" - "1"因为当任一操作数是字符串时，10是字符串连接，而不是加法;但是+总是减法，因此它将其操作数强制为数字。

您需要通过-或+x或parseFloat(x)或（如果它们是整数）Number(x)等来解析它们：

parseInt(x, 10)

示例：

total = parseFloat(this.original())
        + parseFloat(this.improvements())
        - parseFloat(this.depreciation());

$(function() {
  ko.applyBindings(new AppViewModel());
});

function AppViewModel() {
  this.original = ko.observable(0);
  this.improvements = ko.observable(0);
  this.depreciation = ko.observable(0);

  this.total = ko.computed(function() {
    var total = 0;
    total = parseFloat(this.original())
            + parseFloat(this.improvements())
            - parseFloat(this.depreciation());
    return total;
  }, this);
}

如果你要使用数字输入很多，你可能想给自己一个特定的绑定：

<div class="calc-form">
  <label>Original Purchase Price</label>
  <input type="text" id="original" data-bind="value: original" />

  <label>+ Improvements</label>
  <input type="text" id="improvements" data-bind="value: improvements" />

  <label>- Depreciation</label>
  <input type="text" id="depreciation" data-bind="value: depreciation" />

  <input type="button" class="calcbutton" value="Calculate" />
  <input type="button" class="calcbuttonreset" value="reset" />
  <p>= Total</p>
  <span data-bind="text: total"></span>
</div>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>

然后：

// "numValue" binding handler (just an example)
ko.bindingHandlers.numValue = {
  init: function(element, valueAccessor) {
    function numValueHandler() {
      valueAccessor()(parseFloat(this.value));
    }
    $(element).on("input change", numValueHandler)
              .val(ko.unwrap(valueAccessor()));
    ko.utils.domNodeDisposal.addDisposeCallback(element, function() {
      $(element).off("input change", numValueHandler);
    });
  },
  update: function(element, valueAccessor) {
    element.value = ko.unwrap(valueAccessor());
  }
};

<input type="text" id="original" data-bind="numValue: original" />
<!-- ---------------------------------------^^^^^^^^           -->

// "numValue" binding handler (just an example)
ko.bindingHandlers.numValue = {
  init: function(element, valueAccessor) {
    function numValueHandler() {
      valueAccessor()(parseFloat(this.value));
    }
    $(element).on("input change", numValueHandler)
              .val(ko.unwrap(valueAccessor()));
    ko.utils.domNodeDisposal.addDisposeCallback(element, function() {
      $(element).off("input change", numValueHandler);
    });
  },
  update: function(element, valueAccessor) {
    element.value = ko.unwrap(valueAccessor());
  }
};

$(function() {
  ko.applyBindings(new AppViewModel());
});

function AppViewModel() {
  this.original = ko.observable(0);
  this.improvements = ko.observable(0);
  this.depreciation = ko.observable(0);

  this.total = ko.computed(function() {
    var total = 0;
    total = this.original() + this.improvements() - this.depreciation();
    return total;
  }, this);
}

可观察和计算不能正常工作Knockout

1 个答案: