我正在研究 JavaScript 組合函式。假設我有firstname
和lastName作為函式的兩個引數。我希望控制臺在isDoe時顯示。這是我的代碼，但它列印出來未定義。任何想法？謝謝！lastnameundefinded
let name = 'John'
function greetByDefault(firstname,lastname){
return 'Hi ' firstname ' ' lastname '!';
}
if (lastname === undefined){
return 'Doe';
}
console.log(greetByDefault('Jane', 'Doe'));
console.log(greetByDefault(name));
我希望控制臺輸出為：
嗨，簡·多伊！嗨，約翰·多伊！
uj5u.com熱心網友回復：
你可以使用默認值做這樣的事情
let name = 'John'
function greetByDefault(firstname,lastname = 'Doe'){
return 'Hi ' firstname ' ' lastname '!';
}
console.log(greetByDefault('Jane', 'Doe'));
console.log(greetByDefault(name));
console.log(greetByDefault(name, 'Smith'))uj5u.com熱心網友回復：
你必須把所有東西都放進去function
let name = 'John'
function greetByDefault(firstname,lastname){
if (lastname === undefined){
lastname = 'Doe';
}
return 'Hi ' firstname ' ' lastname '!';
}
console.log(greetByDefault('Jane', 'Doe'));
console.log(greetByDefault(name));
uj5u.com熱心網友回復：
let name = 'John'
function greetByDefault(firstname,lastname=''){
if (lastname== ''){
lastname = 'Doe';
}
return 'Hi ' firstname ' ' lastname '!';
}
console.log(greetByDefault('Jane', 'Doe'));
console.log(greetByDefault(name));
轉載請註明出處，本文鏈接：https://www.uj5u.com/qita/534716.html