Question

我正在尝试从对象数组中添加ID属性。显示的结果是01395 - 相反，它应该是27 （因为那是13 + 9 + 5等于）。

我认为代码是连接ID属性而不是添加它们的期望结果。

＆＃13;

var collection = [{
  "Name": "Charlie",
  "ID": "13"
}, {
  "Name": "Emma",
  "ID": "9"
}, {
  "Name": "Bob",
  "ID": "5"
}];

total = 0, //set a variable that holds our total
  id = collection, //reference the element in the "JSON" aka object literal we want
  i = 0;
for (i = 0; i < id.length; i++) { //loop through the array
  total += id[i].ID; //Do the math!
}
console.log(total); //display the result

＆＃13;

JsFiddle：https://jsfiddle.net/3r8vhfb2/

Answer 1

将其转换为Number

Unary plus (+)， unary plus operator位于其操作数之前，并计算其操作数，但尝试将其转换为number，如果它还没有。

＆＃13;

var collection = [{
  "Name": "Charlie",
  "ID": "13"
}, {
  "Name": "Emma",
  "ID": "9"
}, {
  "Name": "Bob",
  "ID": "5"
}];

var total = 0,
  id = collection;
for (var i = 0; i < id.length; i++) {
  total += +id[i].ID;
  //OR total += Number(id[i].ID);
}
console.log(total);

＆＃13;

或使用 Array#reduce ：

＆＃13;

var collection = [{
  "Name": "Charlie",
  "ID": "13"
}, {
  "Name": "Emma",
  "ID": "9"
}, {
  "Name": "Bob",
  "ID": "5"
}];

var total = collection.reduce(function(a, b) {
  return +(a.ID || a) + +(b.ID);
});
console.log(total);

＆＃13;

从对象数组

1 个答案: