​x
 
<!DOCTYPE html>
<html>
<body>
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<h1>JavaScript 数组</h1>
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<p>用旧数组中每个人的全名计算一个新数组：</p>
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<p id="demo"></p>
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<script>
const persons = [
  {firstname : "Malcom", lastname: "Reynolds"},
  {firstname : "Kaylee", lastname: "Frye"},
  {firstname : "Jayne", lastname: "Cobb"}
];
​
document.getElementById("demo").innerHTML = persons.map(getFullName);
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function getFullName(item) {
  return [item.firstname,item.lastname].join(" ");
}
</script>
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</body>
</html>
​