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<!DOCTYPE html>
<html>
<body>
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<h1>JavaScript 对象</h1>
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<h2>Object.keys() 方法</h2>
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<p>Object.keys() 返回带有对象键的 Array Iterator 对象：</p>
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<p id="demo"></p>
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<script>
const person = {
  firstName: "Bill",
  lastName: "Gates",
  age: 19,
  eyeColor: "blue"
};
const keys = Object.keys(person);
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document.getElementById("demo").innerHTML = keys;
</script>
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<p>Internet Explorer 11（及更早版本）不支持 Object.keys()。</p>
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</body>
</html>
​