我如何使用reduce来计算对象中一个值的总和

Question

 const people = [ { name: 'Matt', friend: true, awesomeLevel: 10 }, { name: 'Matias', friend: true, awesomeLevel: 10 }, { name: 'Catie', friend: false, awesomeLevel: 3 }, { name: 'Samantha', friend: false, awesomeLevel: 4 }, { name: 'Jonathan', friend: true, awesomeLevel: 8 }, { name: 'Josh', friend: true, awesomeLevel: 7 } ] let totallyAwesome = people.reduce((acc, ele) => acc + ele.awesomeLevel) console.log(totallyAwesome)

所以我正在尝试使用 reduce 来获得 awesomeLevel 的总和

Answer 1

您需要为累加器添加一个初始值。 否则，第一个元素将作为Array#reduce起始值。

 const people = [ { name: 'Matt', friend: true, awesomeLevel: 10 }, { name: 'Matias', friend: true, awesomeLevel: 10 }, { name: 'Catie', friend: false, awesomeLevel: 3 }, { name: 'Samantha', friend: false, awesomeLevel: 4 }, { name: 'Jonathan', friend: true, awesomeLevel: 8 }, { name: 'Josh', friend: true, awesomeLevel: 7 } ]; let totallyAwesome = people.reduce((acc, ele) => acc + ele.awesomeLevel, 0); // ^ console.log(totallyAwesome);

Answer 2

您只忘记了最后作为第二个参数的 reduce 中的起始值0 （就在回调之后）。

 const people = [ { name: 'Matt', friend: true, awesomeLevel: 10 }, { name: 'Matias', friend: true, awesomeLevel: 10 }, { name: 'Catie', friend: false, awesomeLevel: 3 }, { name: 'Samantha', friend: false, awesomeLevel: 4 }, { name: 'Jonathan', friend: true, awesomeLevel: 8 }, { name: 'Josh', friend: true, awesomeLevel: 7 } ] let totallyAwesome = people.reduce((acc, {awesomeLevel}) => acc + awesomeLevel, 0); console.log(totallyAwesome)