​x
 
<!DOCTYPE html>
<html>
<body>
​
<p>单击按钮可解析不同的字符串。</p>
​
<button onclick="myFunction()">试一试</button>
​
<p id="demo"></p>
​
<script>
function myFunction() {
​
  var fNum1 = parseFloat("12345red");   //返回 12345
  var fNum2 = parseFloat("0xA");    //返回 NaN, 部分浏览器实现会返回 0
  var fNum3 = parseFloat("11.2");   //返回 11.2
  var fNum4 = parseFloat("11.22.33");   //返回 11.22
  var fNum5 = parseFloat("0102");   //返回 102
  var fNum6 = parseFloat("red");    //返回 NaN
​
  document.getElementById("demo").innerHTML =
  fNum1 + "<br>" +
  fNum2 + "<br>" +
  fNum3 + "<br>" +
  fNum4 + "<br>" +
  fNum5 + "<br>" +
  fNum6 + "<br>"
}
</script>
​
</body>
</html>