如何使用NodeJS從串列中排除特定字串

我有用例使用NodeJS動態生成字串串列，如果給定的字串是null我應該從串列中排除該字串。例如：我有productID，productName，productPrice和productType。如果productID是null那么productID欄位應該從串列中排除，如果productName是null則productName應該排除等。IfproductID和productNameare nullthen 這兩個欄位都應該從串列中排除。

我有下面的示例代碼，但這不是一種有效的方法，有人可以建議我們如何使用 NodeJS 以更好的方式實作這個用例。

const test = async () => {

    console.log('generate params')

    var params;

    var productID;
    var productName = "APPLE";
    var productPrice = "12";
    var productType = "Electronics"


    if (productID == null) {
        params = {
            "PRODUCT_NAME": productName,
            "PRODUCT_PRICE": productPrice,
            "PRODUCT_TYPE": productType
        }
    } else if (productName == null) {
        params = {
            "PRODUCT_ID": productID,
            "PRODUCT_PRICE": productPrice,
            "PRODUCT_TYPE": productType
        }
    }
    else if (productPrice == null) {
        params = {
            "PRODUCT_ID": productID,
            "PRODUCT_NAME": productName,
            "PRODUCT_TYPE": productType
        }
    }
    else if (productType == null) {
        params = {
            "PRODUCT_ID": productID,
            "PRODUCT_NAME": productName,
            "PRODUCT_PRICE": productPrice,
        }
    }
    console.log("param value", params)
}

test()

uj5u.com熱心網友回復：

ES6 的最短路徑

params = {
  "PRODUCT_ID": null,
  "PRODUCT_NAME": 'productName',
  "PRODUCT_PRICE": 'productPrice',
  "PRODUCT_TYPE": 'productType' 
}

console.log(params)

//Removes only null
params = Object.entries(params).reduce((a,[k,v]) => (v === null ? a : (a[k]=v, a)), {})

console.log(params)

uj5u.com熱心網友回復：

您可以簡單地創建一個資料結構（在本例中為物件）并在其中添加所有屬性

const collection = { productID, productName, productPrice, productType };

然后你可以使用reduce將它收集到單個物件中，如果它不為空

const params = Object.keys(collection).reduce((acc, curr) => {
    if (collection[curr]) acc[curr] = collection[curr];
    return acc;
  }, {});

單線

const params = Object.keys(collection).reduce((acc, curr) => (collection[curr] ? { ...acc, [curr]: collection[curr] }: acc), {});

const test = async () => {
  console.log("generate params");

  var productID;
  var productName = "APPLE";
  var productPrice = "12";
  var productType = "Electronics";

  const collection = { productID, productName, productPrice, productType };

  const params = Object.keys(collection).reduce((acc, curr) => {
    if (collection[curr]) acc[curr] = collection[curr];
    return acc;
  }, {});
  console.log("param value", params);
};

test();

已編輯

單線

const params = Object.keys(collection).reduce((acc, curr) => collection[curr] ? [...acc, mapping[curr]]: acc, []);

var productID;
var productName = "APPLE";
var productPrice = "12";
var productType = "Electronics";

const collection = { productID, productName, productPrice, productType };
const mapping = {
  produtID: "PRODUCT_ID",
  productName: "PRODUCT_NAME",
  productPrice: "PRODUCT_PRICE",
  productType: "PRODUCT_TYPE",
};
const params = Object.keys(collection).reduce((acc, curr) => {
  if (collection[curr]) acc.push(mapping[curr]);
  return acc;
}, []);
console.log("param value", params);

uj5u.com熱心網友回復：

/* if first value is falsy, use the second value */
params = {
"PRODUCT_ID": productName | null,
"PRODUCT_NAME": productName | null,
"PRODUCT_PRICE": productPrice | null,
"PRODUCT_TYPE": productType | null
}

/*
and if you want to remove keys that are null 
( i don't know why you would want to do this) 
import omitBy and isNull from lodash and do the following
*/

return( _.omitBy( params, _.isNull ));

忘了你需要在降價中轉義下劃線，所以我不得不編輯

標籤：javascript 节点.js json

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