javascript - 通过使用现有元素创建新字段来修改 JSON 对象

Question

我有一个像这样的 javascript 对象:

var obj = {"data":
 [
  {"name":"Alan","height":1.71,"weight":66},
  {"name":"Ben","height":1.82,"weight":90},
  {"name":"Chris","height":1.63,"weight":71}
 ]
 ,"school":"Dover Secondary"
}

如何使用 weight/(height)^2 创建一个名为 BMI 的新字段，使新对象变为:

var new_obj = {"data":
 [
  {"name":"Alan","height":1.71,"weight":66,"BMI":22.6},
  {"name":"Ben","height":1.82,"weight":90,"BMI":27.2},
  {"name":"Chris","height":1.63,"weight":71,"BMI":26.7}
 ]
 ,"school":"Dover Secondary"
}

Answer 1

var persons = obj.data;
var new_obj = {data: [], school: obj.school};
for(var i=0; i<persons.length; i++){
    var person = persons[i];
    new_obj.data.push({
        name: person.name,
        height: person.height,
        weight: person.weight,
        BMI: Math.round(person.weight / Math.pow(person.height, 2)*10)/10;
    });
    /* Use the next line if you don't want to create a new object,
       but extend the current object:*/
    //persons.BMI = Math.round(person.weight / Math.pow(person.height, 2)*10)/10;
}

new_obj 初始化后，循环遍历数组 obj.data。计算 BMI，并将其与所有属性的副本一起添加到 new_obj。如果您不必复制该对象，请查看代码的注释部分。