JS-Dev-101試験無料問題集（149題）「Salesforce Certified JavaScript Developer

出題：1

A developer uses a parsed JSON string to work with user information as in the block below:
01 const userInformation = {
02 "id": "user-01",
03 "email": "[email protected]",
04 "age": 25
05 };
Which two options access the email attribute in the object?

A. userInformation[email]

B. userInformation.get("email")

C. userInformation.email

D. userInformation["email"]

正解：C,D 解答を投票する

解説: (GoShiken メンバーにのみ表示されます)

出題：2

A developer at Universal Containers creates a new landing page based on HTML, CSS, and JavaScript.
To ensure that visitors have a good experience, a script named personalizeWebsiteContent needs to be executed to do some custom initialization when the webpage is fully loaded with HTML content and all related files.
Which statement should be used to call personalizeWebsiteContent based on the above business requirement?

A. window.addEventListener('load', personalizeWebsiteContent);

B. document.addEventListener('onDOMContentLoaded', personalizeWebsiteContent);

C. document.addEventListener('DOMContentLoaded', personalizeWebsiteContent);

D. window.addEventListener('onload', personalizeWebsiteContent);

正解：A 解答を投票する

解説: (GoShiken メンバーにのみ表示されます)

出題：3

A developer executes:
document.cookie;
document.cookie = 'key=John Smith';
What is the behavior?

A. Cookies are not read because line 01 should be document.cookies, but the key value is set and all cookies are wiped.

B. Cookies are read and the key value is set, the remaining cookies are unaffected.

C. Cookies are read and the key value is set, and all cookies are wiped.

D. Cookies are read, but the key value is not set because the value is not URL encoded.

正解：B 解答を投票する

解説: (GoShiken メンバーにのみ表示されます)

出題：4

A developer is setting up a new Node.js server with a client library that is built using events and callbacks.
The library:
Will establish a web socket connection and handle receipt of messages to the server.
Will be imported with require, and made available with a variable called ws.
The developer also wants to add error logging if a connection fails.
Given this information, which code segment shows the correct way to set up a client with two events that listen at execution time?

A. try {
ws.connect(() => {
console.log('Connected to client');
});
} catch(error) {
console.log('ERROR', error);

B. ws.on('connect', () => {
console.log('Connected to client');
});
ws.on('error', (error) => {
console.log('ERROR', error);
});

C. ws.connect(() => {
console.log('Connected to client');
}).catch((error) => {
console.log('ERROR', error);
});

D. ws.on('connect', () => {
console.log('Connected to client');
});
ws.on('error', (error) => {
console.log('ERROR', error);
});

正解：D 解答を投票する

解説: (GoShiken メンバーにのみ表示されます)

出題：5

Given the code below:
let numValue = 1982;
Which three code segments result in a correct conversion from number to string?

A. let strValue = (String)numValue;

B. let strValue = '' + numValue;

C. let strValue = numValue.toString();

D. let strValue = String(numValue);

E. let strValue = numValue.toText();

正解：B,C,D 解答を投票する

解説: (GoShiken メンバーにのみ表示されます)

出題：6

Given a value, which three options can a developer use to detect if the value is NaN?

A. value == NaN

B. value !== value

C. value === Number.NaN

D. Number.isNaN(value)

E. Object.is(value, NaN)

正解：B,D,E 解答を投票する

出題：7

Refer to the code below (assuming Promise.race is intended):
let cat3 = new Promise(resolve =>
setTimeout(resolve, 3000, "Cat 3 completes")
);
Promise.race([cat1, cat2, cat3])
.then(value => {
let result = `${value} the race.`;
})
.catch(err => {
console.log("Race is cancelled:", err);
});
(Assuming cat1 and cat2 are similar to earlier examples: cat2 resolves fastest.) What is the value of result when Promise.race executes?

A. Car 3 completed the race.

B. Car 1 crashed on the race.

C. Race is cancelled.

D. Car 2 completed the race.

正解：D 解答を投票する

解説: (GoShiken メンバーにのみ表示されます)

出題：8

A developer wants to advocate for a mature, well-supported web framework/library instead of a new one (Minimalist.js).
Which two should be recommended?

A. Koa

B. React

C. Express

D. Vue

正解：B,D 解答を投票する

解説: (GoShiken メンバーにのみ表示されます)

出題：9

Given the code below:
01 setCurrentUrl();
02 console.log("The current URL is: " + url);
03
04 function setCurrentUrl() {
05 url = window.location.href;
06 }
What happens when the code executes?

A. The url variable has local scope and line 02 executes correctly.

B. The url variable has global scope and line 02 executes correctly.

C. The url variable has global scope and line 02 throws an error.

D. The url variable has local scope and line 02 throws an error.

正解：B 解答を投票する

解説: (GoShiken メンバーにのみ表示されます)

JS-Dev-101試験無料問題集「Salesforce Certified JavaScript Developer - Multiple Choice 認定」