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如何去除首选国家的重复。我需要在下拉列表中添加所有非洲国家作为首选国家。

我用于此的代码。

preferredCountries: [ "gh", "dz","ao","bj","bw","bf","bi","cm","cf","td","km","cd","dj","eg","gq","er","sz","et","ga","gm","gq","gw","ke","ls","lr","ly","mg","mw","ml","mr","mu","ma","mz","na","ne","ng","rw","sn","sc","sl","so","za","ss","sd","tz","tg","tn","ug","zm","zw" ],
但是同一个国家的所有人都再次出现在列表中。我怎样才能消除重复。

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2 回答 2

1

您可以使用Set在此处获取唯一值，然后使用... 扩展运算符返回数组：

preferredCountries = [ "gh", "dz","ao","bj","bw","bf","bi","cm","cf","td","km","cd","dj","eg","gq","er","sz","et","ga","gm","gq","gw","ke","ls","lr","ly","mg","mw","ml","mr","mu","ma","mz","na","ne","ng","rw","sn","sc","sl","so","za","ss","sd","tz","tg","tn","ug","zm","zw" ];

const uniqueCountries = [...new Set(preferredCountries)];

console.log({ uniqueCountries });
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另一个例子：

const values = [ 'a', 'a', 'a', 'b', 'b', 'b', 'c' ];

// Use spread operator and new Set()
let uniqueValues = [...new Set(values)];

console.log({ uniqueValues });

// Or use Array.from() and new Set()
uniqueValues = Array.from(new Set(values));

console.log({ uniqueValues });
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于 2021-10-14T08:56:06.627 回答
1

您可以通过不同的方式避免数组的重复

let preferredCountries: [ "gh", "dz","ao","bj","bw","bf","bi","cm","cf","td","km","cd","dj","eg","gq","er","sz","et","ga","gm","gq","gw","ke","ls","lr","ly","mg","mw","ml","mr","mu","ma","mz","na","ne","ng","rw","sn","sc","sl","so","za","ss","sd","tz","tg","tn","ug","zm","zw" ],

let NewpreferredCountries= [...new Set(chars)];

console.log(NewpreferredCountries);

另一种方法是

let preferredCountries: [ "gh", "dz","ao","bj","bw","bf","bi","cm","cf","td","km","cd","dj","eg","gq","er","sz","et","ga","gm","gq","gw","ke","ls","lr","ly","mg","mw","ml","mr","mu","ma","mz","na","ne","ng","rw","sn","sc","sl","so","za","ss","sd","tz","tg","tn","ug","zm","zw" ],

let NewpreferredCountries= preferredCountries.filter((c, index) => {
    return preferredCountries.indexOf(c) === index;
});

console.log(NewpreferredCountries);

您还可以使用 forEach() 和 include() 从数组中删除重复项

let preferredCountries: [ "gh", "dz","ao","bj","bw","bf","bi","cm","cf","td","km","cd","dj","eg","gq","er","sz","et","ga","gm","gq","gw","ke","ls","lr","ly","mg","mw","ml","mr","mu","ma","mz","na","ne","ng","rw","sn","sc","sl","so","za","ss","sd","tz","tg","tn","ug","zm","zw" ],

let NewpreferredCountries= [];
preferredCountries.forEach((c) => {
    if (!NewpreferredCountries.includes(c)) {
        NewpreferredCountries.push(c);
    }
});

console.log(NewpreferredCountries);
于 2021-10-14T09:08:06.643 回答