2023年最新のに更新された検証済みの合格させるJavaScript-Developer-I学習ガイドベスト問題集を使おう [Q70-Q90]

2023年最新のに更新された検証済みの合格させるJavaScript-Developer-I学習ガイドベスト問題集を使おう Courses

究極なガイドはJavaScript-Developer-I最新版限定公開

質問 # 70
A developer is required to write a function that calculates the sum of elements in an array but is getting undefined every time the code is executed. The developer needs to find what is missing in the code below.
Const sumFunction = arr => {
Return arr.reduce((result, current) => {
//
Result += current;
//
), 10);
);
Which option makes the code work as expected?

A. Replace line 05 with return result;
B. Replace line 04 with result = result +current;
C. Replace line 03 with if(arr.length == 0 ) ( return 0; )
D. Replace line 02 with return arr.map(( result, current) => (

正解：A

質問 # 71
Which code change should be done for the console to log the following when 'Click me!' is clicked'
> Row log
> Table log

A. Change line 10 to event.stopPropagation (false) ;
B. Remove lines 13 and 14
C. Remove line 10
D. Change line 14 to elem.addEventListener ('click', printMessage, true);

正解：A

質問 # 72
Universal Containers recently launched its new landing page to host a crowd-funding campaign. The page uses an external library to display some third-party ads. Once the page is fully loaded, it creates more than 50 new HTML items placed randomly inside the DOM, like the one in the code below:

All the elements includes the same ad-library-item class, They are hidden by default, and they are randomly displayed while the user navigates through the page.

A. Use the browser to execute a script that removes all the element containing the class ad-library-item.
B. Use the browser console to execute a script that prevents the load event to be fired.
C. Use the DOM inspector to prevent the load event to be fired.
D. Use the DOM inspector to remove all the elements containing the class ad-library-item.

正解：A

質問 # 73
Universal Containers (UC) notices that its application that allows users to search for accounts makes a network request each time a key is pressed. This results in too many requests for the server to handle.
* Address this problem, UC decides to implement a debounce function on string change handler.
What are three key steps to implement this debounce function?
Choose 3 answers:

A. When the search string changes, enqueue the request within a setTimeout.
B. If there is an existing setTimeout and the search string change, allow the existing setTimeout to finish, and do not enqueue a new setTimeout.
C. Ensure that the network request has the property debounce set to true.
D. If there is an existing setTimeout and the search string changes, cancel the existing setTimeout using the persisted timerId and replace it with a new setTimeout.
E. Store the timeId of the setTimeout last enqueued by the search string change handle.

正解：A、B、C

質問 # 74
Refer to the code below:

Which replacement for the conditional statement on line 02 allows a developer to correctly determine that a specific element, myElement on the page had been clicked?

正解：

解説：
event.target.id =='myElement'

質問 # 75
Refer to the code below:

What is the value of result when the code executes?

A. 5 - 10
B. 10 - 5
C. 5 - 5
D. 10 - 10

正解：D

質問 # 76
Which statement accurately describes an aspect of promises?

A. .then ( ) manipulates and returns the original promise.
B. Agruments for the callback function passed to .then ( ) are optional.
C. .Them ( ) cannot be added after a catch.
D. In a , them ( ) function, returning results is not necessary since callback will catch the result of a previous promise.

正解：B

質問 # 77
A team that works on a big project uses npm to deal with projects dependencies.
A developer added a dependency does not get downloaded when they execute npm install.
Which two reasons could be possible explanations for this?
Choose 2 answers

A. The developer missed the option --add when adding the dependency.
B. The developer added the dependency as a dev dependency, and NODE_ENV is set to production.
C. The developer missed the option --save when adding the dependency.
D. The developer added the dependency as a dev dependency, and NODE_ENV Is set to production.

正解：B、C、D

質問 # 78
A developer has an is Dog function that takes one argument cat. They want to schedule the function to run every minute.
What is the correct syntax for scheduling this function?

正解：

解説：
setInterval(isDog, 60000,'cat');

質問 # 79
Refer to the following code:
Let sampletext = 'The quick brown fox Jumps';
A developer need to determine if a certain substring is part of a string.
Which three expressions return true for the give substring? Choose 3 answers

A. sampleText.includes (quick', 4);
B. sampleText.inclides (fox');
C. sampleText.includes (fox' , 3);
D. sampleText.substing ('fox');
E. sampleText.indexof ('quick') 1== -1;

正解：C

質問 # 80
Refer to the code below:
const addBy = ?
const addByEight =addBy(8);
const sum = addBYEight(50);
Which two functions can replace line 01 and return 58 to sum?
Choose 2 answers

A. const addBy = function(num1){
return num1 + num2;
}
B. const addBY = (num1) => (num2) => num1 + num2;
C. const addBy = function(num1){
return function(num2){
return num1 + num2;
}
D. const addBy = (num1) => num1 + num2 ;

正解：B、C

質問 # 81
Refer to the following code:

What is the value of output on line 11?

A. [''foo'':1, ''bar'':2'']
B. [''foo'', ''bar'']
C. [1, 2]
D. An error will occur due to the incorrect usage of the for...of statement on line 07.

正解：D

質問 # 82
developer publishes a new version of a package with new features that do not break backward compatibility. The previous version number was 1.1.3.
Following semantic versioning format, what should the new package version number be?

A. 1.1.4
B. 1.2.3
C. 2.0.0
D. 1.2.0

正解：C

質問 # 83
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. Calling the console.trace (total) method on line 03.
B. Using the debugger command on line 05.
C. Using the debugger command on line 03
D. Wrapping findSubtotal in a console.log() method.

正解：B

質問 # 84
Given the following code:

What will be the first four numbers logged?

A. 0012
B. 0112
C. 0122
D. 0123

正解：C

質問 # 85
Given the following code:

What is the output of line 02?

A. ''object''
B. ''null''
C. ''x''
D. ''Undefined''

正解：A

質問 # 86
Refer to code below:
console.log(0);
setTimeout(() => (
console.log(1);
});
console.log(2);
setTimeout(() => {
console.log(3);
), 0);
console.log(4);
In which sequence will the numbers be logged?

A. 01234
B. 02431
C. 0
D. 02413

正解：B

質問 # 87
Given the code below:
const delay = async delay =>{
return new Promise((resolve,reject)=>{
console.log(1);
setTimeout(resolve,deleay);
});
};
const callDelay = async ()=>{
console.log(2);
const yup = await delay(1000);
console.log(3);
}
console.log(4);
callDelay();
console.log(5);
What is logged to the console?

正解：

解説：
4 2 1 5 3

質問 # 88
Given the requirement to refactor the code above to JavaScript class format, which class definition is correct?

正解：A

質問 # 89
Given the JavaScript below:

Which code should replace the placeholder comment on line 06 to hide accounts that do not match the search string?