# 元ツイ
x.com
# 1. 普通に if で分岐
ifで分岐
type Apartment = {
metersToStation: number;
ageOfBuilding: number;
options: string[];
};
const apartment: Apartment = {
metersToStation: 400,
ageOfBuilding: 5,
options: ["ShoeLocker", "AutoLock"],
};
const salesPoints1: string[] = [];
if (apartment.metersToStation < 1000) {
salesPoints1.push("駅近");
}
if (apartment.ageOfBuilding < 5) {
salesPoints1.push("築浅");
}
if (apartment.options.includes("AutoLock")) {
salesPoints1.push("セキュリティ充実");
}
# 2. 短絡評価と filter と型ガード
短絡評価とfilterと型ガード
type Apartment = {
metersToStation: number;
ageOfBuilding: number;
options: string[];
};
const apartment: Apartment = {
metersToStation: 400,
ageOfBuilding: 5,
options: ["ShoeLocker", "AutoLock"],
};
const salesPoints2: string[] = [
apartment.metersToStation < 1000 && "駅近",
apartment.metersToStation < 5 && "築浅",
apartment.options.includes("AutoLock") && "セキュリティ充実",
].filter<string>((point): point is string => typeof point === "string");
# 3. ジェネレーター
ジェネレーター
type Apartment = {
metersToStation: number;
ageOfBuilding: number;
options: string[];
};
const apartment: Apartment = {
metersToStation: 400,
ageOfBuilding: 5,
options: ["ShoeLocker", "AutoLock"],
};
function* makeSalesPoint(apartment: Apartment) {
if (apartment.metersToStation < 1000) yield "駅近";
if (apartment.ageOfBuilding < 5) yield "築浅";
if (apartment.options.includes("AutoLock")) yield "セキュリティ充実";
}
const salesPoints3: string[] = [...makeSalesPoint(apartment)];
# 全体コード
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