JavaScript Developer I 実際試験問題と解答 - 模擬練習 - 受験自信を増やす

Question No : 1
A developer has a web server running with Node.js. The command to start the web server is node server.js. The web server started having latency issues. Instead of a one second turnaround for web requests, the developer now sees a five second turnaround.
Which command can the web developer run to see what the module is doing during the latency period?

A.NODE_DEBUG=true node server.js
B.DEBUG=http, https node server.js
C.NODE_DEBUG=http,https node server.js
D.DEBUG=true node server.js

正解:

Question No : 2
developer is trying to convince management that their team will benefit from using Node.js for a backend server that they are going to create. The server will be a web server that handles API requests from a website that the team has already built using HTML, CSS, and JavaScript.
Which three benefits of Node.js can the developer use to persuade their manager? Choose 3 answers:

A.Installs with its own package manager to install and manage third-party libraries.
B.Ensures stability with one major release every few years.
C.Performs a static analysis on code before execution to look for runtime errors.
D.Executes server-side JavaScript code to avoid learning a new language.
E.User non blocking functionality for performant request handling .

正解:

Question No : 3
Refer to the code below?
Let searchString = ‘ look for this ’;
Which two options remove the whitespace from the beginning of searchString? Choose 2 answers

A.searchString.trimEnd();
B.searchString.trimStart();
C.trimStart(searchString);
D.searchString.replace(/*\s\s*/, ‘’);

正解:

Question No : 4
A developer wants to create an object from a function in the browser using the code below:
Function Monster() { this.name = ‘hello’ };
Const z = Monster();
What happens due to lack of the new keyword on line 02?

A.The z variable is assigned the correct object.
B.The z variable is assigned the correct object but this.name remains undefined.
C.Window.name is assigned to ‘hello’ and the variable z remains undefined.
D.Window.m is assigned the correct object.

正解:

Question No : 5
A developer has a formatName function that takes two arguments, firstName and lastName and returns a string. They want to schedule the function to run once after five seconds.
What is the correct syntax to schedule this function?

A.setTimeout (formatName(), 5000, "John", "BDoe");
B.setTimeout (formatName('John', ‘'Doe'), 5000);
C.setTimout(() => { formatName("John', 'Doe') }, 5000);
D.setTimeout ('formatName', 5000, 'John", "Doe');

正解:

Question No : 6
A developer has code that calculates a restaurant bill, but generates incorrect answers while testing the code:
function calculateBill ( items ) {
let total = 0;
total += findSubTotal(items);
total += addTax(total);
total += addTip(total);
return total;
}
Which option allows the developer to step into each function execution within calculateBill?

A.Using the debugger command on line 05.
B.Using the debugger command on line 03
C.Calling the console.trace (total) method on line 03.
D.Wrapping findSubtotal in a console.log() method.

正解:

Question No : 7
Given the following code:
document.body.addEventListener(‘ click ’, (event) => {
if (/* CODE REPLACEMENT HERE */) {
console.log(‘button clicked!’);
)
});
Which replacement for the conditional statement on line 02 allows a developer to correctly determine that a button on page is clicked?

A.Event.clicked
B.e.nodeTarget ==this
C.event.target.nodeName == ‘BUTTON’
D.button.addEventListener(‘click’)

正解:

Question No : 8
Refer to the code below:
Let textValue = ’1984’;
Which code assignment shows a correct way to convert this string to an integer?

A.let numberValue = Number(textValue);
B.Let numberValue = (Number)textValue;
C.Let numberValue = textValue.toInteger();
D.Let numberValue = Integer(textValue);

正解:

Question No : 9
Which three statements are true about promises? Choose 3 answers

A.The executor of a new Promise runs automatically.
B.A Promise has a .then() method.
C.A fulfilled or rejected promise will not change states .
D.A settled promise can become resolved.
E.A pending promise can become fulfilled, settled, or rejected.

正解:

Question No : 10
Refer to the code below:
let sayHello = () => {
console.log (‘Hello, world!’);
};
Which code executes sayHello once, two minutes from now?

A.setTimeout(sayHello, 12000);
B.setInterval(sayHello, 12000);
C.setTimeout(sayHello(), 12000);
D.delay(sayHello, 12000);

正解:

Question No : 11
A developer wants to iterate through an array of objects and count the objects and count the objects whose property value, name, starts with the letter N.
Const arrObj = [{“name” : “Zach”} , {“name” : “Kate”},{“name” : “Alise”},{“name” :
“Bob”},{“name” :
“Natham”},{“name” : “nathaniel”}
Refer to the code snippet below:
01 arrObj.reduce(( acc, curr) => {
02 //missing line 02
02 //missing line 03
04 ). 0);
Which missing lines 02 and 03 return the correct count?

A.Const sum = curr.startsWith(‘N’)? 1: 0; Return acc +sum
B.Const sum = curr.name.startsWith(‘N’)? 1: 0; Return acc +sum
C.Const sum = curr.startsWIth(‘N’)? 1: 0; Return curr+ sum
D.Const sum = curr.name.startsWIth(‘N’)? 1: 0; Return curr+ sum

正解:

Question No : 12
A developer wants to define a function log to be used a few times on a single-file JavaScript script.
01 // Line 1 replacement
02 console.log('"LOG:', logInput);
03 }
Which two options can correctly replace line 01 and declare the function for use? Choose 2 answers

A.function leg(logInput) {
B.const log(loginInput) {
C.const log = (logInput) => {
D.function log = (logInput) {

正解:

Question No : 13
Why would a developer specify a package.jason as a developed forge instead of a dependency?

A.It is required by the application in production.
B.It is only needed for local development and testing.
C.Other required packages depend on it for development.
D.It should be bundled when the package is published.

正解:

Question No : 14
Refer to the code below:

After running this code, which result is displayed on the console?

A.> true > false
B.> 5 >undefined
C.> 5 > -1
D.> 5 > 0

正解:

Question No : 15
developer has a web server running with Node.js. The command to start the web server is node server,js. The web server started having latency issues. Instead of a one second turn around for web requests, the developer now sees a five second turnaround,
Which command can the web developer run to see what the module is doing during the latency period?

A.DEBUG = http, https node server.js
B.NODE_DEBUG =http, https node server.js
C.DEBUG =true node server.js
D.NODE_DEBUG =true node server.js

正解:

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