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<!DOCTYPE html>
<html>
<body>
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<p>单击按钮调用新的 myMet() 方法，并使用新的 myProp 属性显示该月的名称。</p>
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<button onclick="myFunction()">试一试</button>
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<p id="demo"></p>
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<script>
Date.prototype.myMet = function() {
  if (this.getMonth() == 0){this.myProp = "January"};
  if (this.getMonth() == 1){this.myProp = "February"};
  if (this.getMonth() == 2){this.myProp = "March"};
  if (this.getMonth() == 3){this.myProp = "April"};
  if (this.getMonth() == 4){this.myProp = "May"};
  if (this.getMonth() == 5){this.myProp = "June"};
  if (this.getMonth() == 6){this.myProp = "July"};
  if (this.getMonth() == 7){this.myProp = "August"};
  if (this.getMonth() == 8){this.myProp = "September"};
  if (this.getMonth() == 9){this.myProp = "October"};
  if (this.getMonth() == 10){this.myProp = "November"};
  if (this.getMonth() == 11){this.myProp = "December"};
};
​
function myFunction() {
  var d = new Date();
  d.myMet();
  document.getElementById("demo").innerHTML = d.myProp;
}
</script>
​
</body>
</html>
​