为什么我的对象显示为"[object Object]"？

Question

我试图按年龄对一系列记录进行冒泡,但我得到的只是:

[object Object],[object Object],[object Object]

如何让它显示记录的值？

students = [
    {name: "timothy", age: "9"},
    {name: "claire",  age: "12"},
    {name: "michael", age: "20"}
];

for (var i = 0; i < students.length; i++) {
    for (var j = i + 1; j < students.length; j++) {
        if (Number(students[i].age) > Number(students[j].age)) {
            tempValue = students[j].age;
            students[j].age = students[i].age;
            students[i].age = tempValue;
        }
    }
}

alert(students);

Answer 1

默认情况下,JavaScript中的所有对象在"[object Object]"转换为字符串时都会转向(如果是这样alert()).

您可以尝试:

• 使用console.log或调试器来检查数组(而不是使用alert())

  console.log(students);
  //Open your browser's developer tools to see the console.
  //Try F12, ctrl+shift+J or ctrl+shift+I as shortcuts
  

• 使用该JSON.stringify函数序列化对象.

  JSON.stringify({a:1});
  //yields '{"a":1}'
  

• 为对象提供自定义toString方法

  var x = {
      a : 17,
      toString: function(){
          return 'I have a ' + this.a;
      }
  };
  alert(x); //gives "I have a 17"