[英]JavaScript: Reduce an array to nested objects
所以假设我的数组看起来像这样:
let langArr = [
["python", "blue"]
,["python", "blue"]
,["c++", "red"]
,["java", "yellow"]
,["javascript", "lime"]
,["shell", "green"]
,["c++", "red"]
];
我想要的是这样的:
{
python: {
count: 2
color: "blue"
}
c++: {
count: 2
color: "red"
}
java: {
count: 1
color: "yellow"
}
and so on...
}
我试过这样的reduce方法:
let langCount = langArr.reduce((lang, [name, color]) => {
lang[name] = (lang[name] || 0) + 1;
lang[color] = 'color';
return lang;
}, {});
console.log(langCount);
但我得到这个输出:
{
python: 2
blue: "color"
c++: 2
red: "color"
java: 1
yellow: "color"
and so on...
}
每种语言都需要一个对象。
如果lang[name]
为falsy ,则此方法将对象作为默认值,例如undefined
。
图案
variable = variable || value;
使用逻辑 OR ||
:
variable
有一个真值,取这个值,variable
有一个假值, 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);
你可以使用这个:
array.reduce((acc, current) => {
if(!acc.hasOwnProperty(current[0])){
acc[current[0]] = {count: 0, color: current[1]};
}
acc[current[0]].count += 1;
return acc;
}, {});
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.