在新创建的对象中定义 SetterGetter
JavaScript 允许我们在对象文字语法中定义 getter 和 setter。这是一个例子:
var date = {
year: '2017',
month: '02',
day: '27',
get date() {
// Get the date in YYYY-MM-DD format
return `${this.year}-${this.month}-${this.day}`
},
set date(dateString) {
// Set the date from a YYYY-MM-DD formatted string
var dateRegExp = /(\d{4})-(\d{2})-(\d{2})/;
// Check that the string is correctly formatted
if (dateRegExp.test(dateString)) {
var parsedDate = dateRegExp.exec(dateString);
this.year = parsedDate[1];
this.month = parsedDate[2];
this.day = parsedDate[3];
}
else {
throw new Error('Date string must be in YYYY-MM-DD format');
}
}
};
访问 date.date
属性将返回值 2017-02-27
。设置 date.date = '2018-01-02
将调用 setter 函数,然后解析字符串并设置 date.year = '2018'
,date.month = '01'
和 date.day = '02'
。尝试传递格式不正确的字符串(例如 hello
)会引发错误。