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function pick(object, ...keys){
let result = Object.create(null);
for(let i = 0; i < keys.length; i++){
result[keys[i]] = object[keys[i]];
}
return result;
}
//报错,不能再剩余参数后使用具名函数
function pick(object, ...keys, last){
let result = Object.create(null);
for(let i = 0; i < keys.length; i++){
result[keys[i]] = object[keys[i]];
}
return result;
let object = {
//语法错误:不能在setter中使用剩余参数
set name(...value){
// 一些操作
}
}
function Person(name) {
this.name = name;
};
var person = new Person('lai');
var notPerson = Person('hua');
console.log(person); // [Object object]
console.log(notPerson); //"undefined"
function Person(name) {
if(this instanceOf Person){
this.name = name;
}else{
throw new error('You must use new with Person')
}
}
var person = new Person('lai');
var notPerson = new Person('hua'); //P
块级函数
The text was updated successfully, but these errors were encountered:
带参数默认值的函数
1. 什么是带默认值的函数
2. 带默认值的函数的性质
块级函数
The text was updated successfully, but these errors were encountered: