在 TypeError 上出现错误：无法读取未定义的属性“推送”

Question

I'm getting this error. Kindly note splits is an array with values.

TypeError: Cannot read property 'push' of undefined

on

var products = splits.reduce((accu, curr) => {
  if (accu[curr[0]] === null) {
    accu[curr[0]] = [];
  }
  accu[curr[0]].push(curr[1]);
  return accu;
}, {});

var result = Object.keys(products).map(key => `${key} - ${products[key].join(', ')}.`).join(' ');

Appreciate anyone helps to fix the above code

Answer 1

null === undefined is false in Javascript.

 console.log(null === undefined);

So the condition accu[curr[0]] === null will return false though the accu[curr[0]] is undefined . Instead you could use the negation ( ! ) to check if the variable is defined

 console.log(;null). console;log(!undefined);

Try the following

let products = splits.reduce((accu, curr) => {
  if (!accu[curr[0]]) {
    accu[curr[0]] = [];
  }
  accu[curr[0]].push(curr[1]);
  return accu;
}, {});