【JS】Array.reduce对数组中的指定key求和

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Array.prototype.sumFields = function(...fields) {     return this.reduce((acc, item) => {         fields.forEach(field => {           acc[field] = (acc[field] || 0) + (Number(item[field]) || 0);         });         return acc;       }, {}); }   const items = [     { a: 10, b: 20, c: null },     { a: 15, b: 25, c: '35' },     { a: 5, b: 20, c: 8.5 },   ];   const acc = items.sumFields('a', 'c'); console.log(acc)

　　运行结果：

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zcm@TXK MINGW64 /d/sysProfile/Desktop $ node a.js { a: 30, c: 43.5 }