百分比计算误差

Question

我试图计算数字的百分比（取自一个文本字段），并将计算值设置为另一个表单字段。为此，我尝试了下面的代码，但我发现js正在检测的键事件/小数位数不匹配。

例如，如果我在第一个输入字段中提供100（以计算1.75的百分比），根据我的js代码，我预计是1.75，但在第二个文本字段中是0.175。我知道这是一个非常简单的计算，但我无法解决这个问题。

var reFee = document.getElementById("Estimated Referral Fee");
var LnAmt = document.getElementById("Loan Amount");
reFee.disabled = true;

LnAmt.onkeydown =
  function isNumber(evt) {

    evt = (evt) ? evt : window.event;
    var charCode = (evt.which) ? evt.which : evt.keyCode;
    if (charCode > 31 && (charCode < 48 || charCode > 57)) {
      return false;
    }
    calcPer(LnAmt.value);
  }

function calcPer(amtval) {
  var pernum = 1.75;
  reFee.value = (pernum / 100) * amtval;
}

<div class="form-group">
  <label class="control-label col-sm-2">Loan Amount</label>
  <div class="col-sm-10">
    <input id="Loan Amount" placeholder="Provide Loan Amount" data-toggle="tooltip" data-original-title="Provide Loan Amount" required="required" class="form-control" name="Loan Amount" type="text" value="">
    <span class="help-block"></span>
  </div>
</div>
<div class="form-group">
  <label class="control-label col-sm-2">Estimated Referral Fee</label>
  <div class="col-sm-10">
    <input id="Estimated Referral Fee" placeholder="Your referral fee" data-toggle="tooltip" data-original-title="Your referral fee" required="required" class="form-control" name="Estimated Referral Fee" type="text" value="" disabled="">
    <span class="help-block"></span>
  </div>
</div>

Answer 1

js prettyprint-override">var reFee = document.getElementById("Estimated Referral Fee");
var LnAmt = document.getElementById("Loan Amount");
reFee.disabled = true;

LnAmt.onkeyup =
  function isNumber(evt) {

    evt = (evt) ? evt : window.event;
    var charCode = (evt.which) ? evt.which : evt.keyCode;
    if (charCode > 31 && (charCode < 48 || charCode > 57)) {
      return false;
    }
    calcPer(LnAmt.value);
  }

function calcPer(amtval) {
  var pernum = 1.75;
  reFee.value = (pernum / 100) * amtval;
}

<div class="form-group">
  <label class="control-label col-sm-2">Loan Amount</label>
  <div class="col-sm-10">
    <input id="Loan Amount" placeholder="Provide Loan Amount" data-toggle="tooltip" data-original-title="Provide Loan Amount" required="required" class="form-control" name="Loan Amount" type="text" value="">
    <span class="help-block"></span>
  </div>
</div>
<div class="form-group">
  <label class="control-label col-sm-2">Estimated Referral Fee</label>
  <div class="col-sm-10">
    <input id="Estimated Referral Fee" placeholder="Your referral fee" data-toggle="tooltip" data-original-title="Your referral fee" required="required" class="form-control" name="Estimated Referral Fee" type="text" value="" disabled="">
    <span class="help-block"></span>
  </div>
</div>