[英]JavaScript: Reduce an array to nested objects
所以假設我的數組看起來像這樣:
let langArr = [
["python", "blue"]
,["python", "blue"]
,["c++", "red"]
,["java", "yellow"]
,["javascript", "lime"]
,["shell", "green"]
,["c++", "red"]
];
我想要的是這樣的:
{
python: {
count: 2
color: "blue"
}
c++: {
count: 2
color: "red"
}
java: {
count: 1
color: "yellow"
}
and so on...
}
我試過這樣的reduce方法:
let langCount = langArr.reduce((lang, [name, color]) => {
lang[name] = (lang[name] || 0) + 1;
lang[color] = 'color';
return lang;
}, {});
console.log(langCount);
但我得到這個輸出:
{
python: 2
blue: "color"
c++: 2
red: "color"
java: 1
yellow: "color"
and so on...
}
每種語言都需要一個對象。
如果lang[name]
為falsy ,則此方法將對象作為默認值,例如undefined
。
圖案
variable = variable || value;
使用邏輯 OR ||
:
variable
有一個真值,取這個值,variable
有一個假值, value
代替。 let langArr = [["python", "blue"], ["python", "blue"], ["c++", "red"], ["java", "yellow"], ["javascript", "lime"], ["shell", "green"], ["c++", "red"]], langCount = langArr.reduce((lang, [name, color]) => { lang[name] = lang[name] || { count: 0, color }; lang[name].count++; return lang; }, {}); console.log(langCount);
你可以使用這個:
array.reduce((acc, current) => {
if(!acc.hasOwnProperty(current[0])){
acc[current[0]] = {count: 0, color: current[1]};
}
acc[current[0]].count += 1;
return acc;
}, {});
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.