用数组 javascript 过滤掉数组

Question

如何过滤掉对象数组 a，其中 item1 是数组 b 的一部分？

a = [
{
    "item1": "apple",
    "item2": "banana"
},
{
    "item1": "apple",
    "item2": "cherry"
},
{
    "item1": "melon",
    "item2": "cherry"
},
{
    "item1": "banana",
    "item2": "melon"
}]



b = [ "apple", "banana"]

预期的数组将是：

expected_array = [{
                     "item": "melon",
                     "item2": "cherry"
                  }]

我试过：

a.filter(el => !b.includes(el.item1))

但生成的数组与原始数组的长度相同。

我在 Node Red 中执行此操作，这是我的测试设置：

[{"id":"ab67374c.c64458","type":"debug","z":"42edc0b9.7ba91","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","statusVal":"","statusType":"auto","x":2040,"y":300,"wires":[]},{"id":"3fbdbc18.951c94","type":"function","z":"42edc0b9.7ba91","name":"cycle counter","func":"\n\nmsg.payload = msg.payload.filter(el => !msg.exclude.includes(el.altname));\n\nnode.warn(msg.payload);\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":1810,"y":320,"wires":[["ab67374c.c64458"]]},{"id":"b4b2e91f.8e4368","type":"inject","z":"42edc0b9.7ba91","name":"","props":[{"p":"payload"},{"p":"exclude","v":"[[\"melon\"],[\"banana\"]]","vt":"json"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"[{\"altname\":\"melon\"},{\"altname\":\"cherry\"},{\"altname\":\"banana\"}]","payloadType":"json","x":1650,"y":320,"wires":[["3fbdbc18.951c94"]]}]

Answer 1

正如其他人在评论中所说，您的代码很好，但您需要将过滤器函数的输出分配给一个变量。

let a = [{
    "item1": "apple",
    "item2": "banana"
  },
  {
    "item1": "apple",
    "item2": "cherry"
  },
  {
    "item1": "melon",
    "item2": "cherry"
  },
  {
    "item1": "banana",
    "item2": "melon"
  }
];
let b = ["apple", "banana"];

// assign filter output to variable `c`
let c = a.filter(el => !b.includes(el.item1));

console.log(c); // your output

用数组 javascript 过滤掉数组

filter out array with array javascript

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node-red