JavaScript-Developer-I無料問題集「Salesforce Certified JavaScript Developer (JS-Dev-101)」

質問 1

Refer to the code below:
01 let sayHello = () = > {
02 console.log( ' Hello, World! ' );
03 };
Which code executes sayHello once , two minutes from now?

（A）delay(sayHello, 120000);

（B）setTimeout(sayHello(), 120000);

（C）setTimeout(sayHello, 120000);

（D）setInterval(sayHello, 120000);

正解：C 解答を投票する

解説: (JPNTest メンバーにのみ表示されます)

質問 2

let sampleText = " The quick brown fox jumps " ;
Which three expressions return true for a substring?

（A）sampleText.indexOf( ' quick ' ) > -1;

（B）sampleText.include( ' fox ' ) !== -1;

（C）sampleText.indexOf( ' fox ' ) !== -1;

（D）sampleText.includes( ' fox ' );

（E）sampleText.indexOf( ' Quick ' ) !== -1;

正解：A、C、D 解答を投票する

解説: (JPNTest メンバーにのみ表示されます)

質問 3

Refer to the code below:
01 x = 3.14;
02
03 function myFunction() {
04 ' use strict ' ;
05 y = x;
06 }
07
08 z = x;
09 myFunction();
Considering the implications of ' use strict ' on line 04, which three statements describe the execution of the code?

（A）z is equal to 3.14.

（B）' use strict ' has an effect only on line 05.

（C）' use strict ' is hoisted, so it has an effect on all lines.

（D）' use strict ' has an effect between line 04 and the end of the file.

（E）Line 05 throws an error.

正解：A、B、E 解答を投票する

解説: (JPNTest メンバーにのみ表示されます)

質問 4

Which two implementations of utils.js support foo and bar?

（A）import { foo, bar } from " ./helpers/utils.js " ;
export { foo, bar };

（B）export default class {
foo() { return ' foo ' ; }
bar() { return ' bar ' ; }
}

（C）const foo = () = > { return ' foo ' ; };
const bar = () = > { return ' bar ' ; };
export { foo, bar };

（D）const foo = () = > { return ' foo ' ; };
const bar = () = > { return ' bar ' ; };
export default { foo, bar };

正解：A、C 解答を投票する

解説: (JPNTest メンバーにのみ表示されます)

質問 5

Refer to the code:
01 console.log( ' Start ' );
02 Promise.resolve( ' Success ' ).then(function(value) {
03 console.log( ' Success ' );
04 });
05 console.log( ' End ' );
What is the output after the code executes successfully?

（A）Success
Start
End

（B）Start
Success
End

（C）Start
End
Success

（D）End
Start
Success

正解：C 解答を投票する

解説: (JPNTest メンバーにのみ表示されます)

質問 6

Which three browser specific APIs are available for developers to persist data between page loads?

（A）global variables

（B）IIFEs

（C）localStorage

（D）indexedDB

（E）cookies

正解：C、D、E 解答を投票する

解説: (JPNTest メンバーにのみ表示されます)

質問 7

Refer to the code below:
01 function myFunction(reassign) {
02 let x = 1;
03 var y = 1;
04
05 if (reassign) {
06 let x = 2;
07 var y = 2;
08 console.log(x);
09 console.log(y);
10 }
11
12 console.log(x);
13 console.log(y);
14 }
What is displayed when myFunction(true) is called?

（A）2 2 undefined undefined

（B）2 2 1 2

（C）2 2 1 1

（D）2 2 2 2

正解：B 解答を投票する

解説: (JPNTest メンバーにのみ表示されます)

質問 8

Refer to the code below:
01 const myFunction = arr = > {
02 return arr.reduce((result, current) = > {
03 return result + current;
04 }, 10);
05 }
What is the output of this function when called with an empty array?

（A）Returns NaN

（B）Returns 0

（C）Returns 5 # (Text here appears to be a typo; correct value is 10, see explanation.)

（D）Throws an error

正解：C 解答を投票する

解説: (JPNTest メンバーにのみ表示されます)

質問 9

A developer creates a new web server that uses Node.js. It imports a server library that uses events and callbacks for handling server functionality. The server library is imported with require and is made available to the code by a variable named server. The developer wants to log any issues that the server has while booting up.
Which code logs an error at boot time with an event?

（A）server.catch((error) = > {
console.log( ' ERROR ' , error);
});

（B）server.on( ' error ' , (error) = > {
console.log( ' ERROR ' , error);
});

（C）try {
server.start();
} catch(error) {
console.log( ' ERROR ' , error);
}

（D）server.error((error) = > {
console.log( ' ERROR ' , error);
});

正解：B 解答を投票する

解説: (JPNTest メンバーにのみ表示されます)

JavaScript-Developer-I 無料問題集「Salesforce Certified JavaScript Developer (JS-Dev-101)」

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