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如何添加到 Javascript 中的函數？

JavaScript

不負相思意 2023-04-20 16:21:56

更改 removeproduct 代碼如下。并將 product-id 作為參數傳遞給函數。const removeProduct = (productId) => { let cart = JSON.parse(localStorage.getItem("cartProduct")); cart = cart.filter(productData => productData._id !== productId) localStorage.setItem("cartProduct", JSON.stringify(cart)); window.location.reload(); };有關filter方法的更多詳細信息，請參閱 MDN 文檔。如下更改您的組件以將 id 參數傳遞給函數。<Container> <div> { cart.map(item => ( <p>item.productName</p> <p>item.price</p> <i class="fas fa-trash-alt mr-1" style={{ color: '#ff6b6b' }} onClick={() => removeProduct(item._id)} ></i> )) } </div></Container>

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4 回答

慕的地6264312

TA貢獻1817條經驗獲得超6個贊

在返回之前，newArr您可以檢查它的長度，如果它為零，則返回“No matches”。

let people = [{

studying: "JS",

age: "33"

{

studying: "JS",

age: "137"

{

studying: "education",

age: "1897374"

}

];

function returnArrOfNames(people, string) {

let newArr = []

for (let i = 0; i < people.length; i++) {

if (people[i].studying === string) {

newArr.push(people[i].name)

}

if (newArr.length === 0) {

return "No matches";

}

return newArr

}

console.log(returnArrOfNames(people, "JS"));

反對回復 2023-04-20

有只小跳蛙

TA貢獻1824條經驗獲得超8個贊

編輯：對不起，我發布了與其他人相同的答案。

您可以只在 for 循環之外添加該 if 語句。像這樣：

let people = [

{name : "Nick",

studying : "JS",

age : "33"},

{name : "Joseph",

studying : "JS",

age : "137"},

{name : "Jeff",

studying : "education",

age : "1897374"}

];

function returnArrOfNames(people, string) {

let newArr = []

for (let i = 0; i < people.length; i++) {

if (people[i].studying === string) {

newArr.push(people[i].name)

}

if (newArr.length == 0){

return console.log("no matches")

}

console.log(newArr);

return newArr

}

returnArrOfNames(people, "JS")

反對回復 2023-04-20

白衣非少年

TA貢獻1155條經驗獲得超0個贊

更簡單的是array.reduce方法，使用三元條件返回

const people =

[ { name: 'Nick', studying: 'JS', age: '33' }

, { name: 'Joseph', studying: 'JS', age: '137' }

, { name: 'Jeff', studying: 'education', age: '1897374' }

]

function returnArrOfNames(arr, study)

{

let newArr = arr.reduce((a,c)=>

{

if (c.studying===study) a.push(c.name)

return a

}, [])

return newArr.length ? newArr : 'no matches'

}

console.log(' JS ? ->', returnArrOfNames(people, "JS") ) // Array [ "Nick", "Joseph" ]

console.log(' xx ? ->', returnArrOfNames(people, "xx") ) // "no matches"

.as-console-wrapper { max-height: 100% !important; top: 0; }

反對回復 2023-04-20

小唯快跑啊

TA貢獻1863條經驗獲得超2個贊

您可以利用Array prototype's map和filter方法來獲得結果：

let people = [{

studying: "JS",

age: "33"

{

studying: "JS",

age: "137"

{

studying: "education",

age: "1897374"

}

];

function returnArrOfNames(people = [], studying) {

const NO_MATCHES = 'No Matches'

const isEmpty = people.length === 0

if (isEmpty) {

return NO_MATCHES

}

const filterFn = i => i.studying === studying

const filteredPeople = people.filter(filterFn)

const isEmptyFilteredPeople = filteredPeople.length === 0;

if(isEmptyFilteredPeople) return NO_MATCHES

const mapFn = i => i.name

const mappedPeople = filteredPeople.map(mapFn);

return mappedPeople

}

console.log(returnArrOfNames(people, "JS"));

反對回復 2023-04-20

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如何添加到 Javascript 中的函數？

如何添加到 Javascript 中的函數？