javascript - 更新或添加值到列表

Question

如果找不到名称，您将如何更新库存(基于名称)或添加。

var inventory = [
    {name: 'apples', quantity: 2},
    {name: 'bananas', quantity: 0},
    {name: 'cherries', quantity: 5}
];

例如，以下将更新库存:

const fruit = {name: 'bananas', quantity: 1}
inventory = inventory.map(f => f.name===fruit.name ? fruit : f);

这可以用来添加到库存中:

const fruit = {name: 'oranges', quantity: 2}
if (!inventory.find(f => f.name===fruit.name)) inventory.push(fruit)

但我正在寻找一种解决方案，它可以做到这两点，并且最好使用箭头函数而不是索引 - 如果可能的话。

Answer 1

您可以使用 findIndex :

var idx = inventory.findIndex(f => f.name === fruit.name);
inventory[idx < 0 ? inventory.length : idx] = fruit;

var inventory = [
    {name: 'apples', quantity: 2},
    {name: 'bananas', quantity: 0},
    {name: 'cherries', quantity: 5}
];

var fruit = {name: 'bananas', quantity: 1}

var idx = inventory.findIndex(f => f.name === fruit.name);
inventory[idx < 0 ? inventory.length : idx] = fruit;

var fruit = {name: 'oranges', quantity: 2}

var idx = inventory.findIndex(f => f.name === fruit.name);
inventory[idx < 0 ? inventory.length : idx] = fruit;

console.log(inventory);

如果您想合并两个对象数组(而不是将单个对象合并到一个数组)，那么这种方法将是二次方的。你应该看到 JavaScript merging objects by id相反。