Salesforce JavaScript-Developer-I 問題集

質問 1：
Code:
01 let array = [1, 2, 3, 4, 4, 5, 4, 4];
02 for (let i = 0; i < array.length; i++) {
03 if (array[i] === 4) {
04 array.splice(i, 1);
05 i--;
06 }
07 }
What is the value of array after execution?
A. [1,2,3,4,5,4]
B. [1,2,3,5]
C. [1,2,3,4,5,4,4]
D. [1,2,3,4,4,5,4]
正解：B
解説: (Topexam メンバーにのみ表示されます)

質問 2：
Given the code below:
01 const delay = async delay = > {
02 return new Promise((resolve, reject) = > {
03 console.log(1);
04 setTimeout(resolve, delay);
05 });
06 };
07
08 const callDelay = async () = > {
09 console.log(2);
10 const yup = await delay(1000);
11 console.log(3);
12 };
13
14 console.log(4);
15 callDelay();
16 console.log(5);
What is logged to the console?
A. 1 4 2 3 5
B. 4 2 1 5 3
C. 4 5 1 2 3
D. 4 2 1 5 3
正解：D
解説: (Topexam メンバーにのみ表示されます)

質問 3：
Refer to the code below:
01 let o = {
02 get js() {
03 let city1 = String( ' St. Louis ' );
04 let city2 = String( ' New York ' );
05
06 return {
07 firstCity: city1.toLowerCase(),
08 secondCity: city2.toLowerCase(),
09 }
10 }
11 }
What value can a developer expect when referencing o.js.secondCity?
A. An error
B. ' new york '
C. undefined
D. ' New York '
正解：B
解説: (Topexam メンバーにのみ表示されます)

質問 4：
JavaScript:
01 function Tiger() {
02 this.type = ' Cat ' ;
03 this.size = ' large ' ;
04 }
05
06 let tony = new Tiger();
07 tony.roar = () = > {
08 console.log( ' They\ ' re great! ' );
09 };
10
11 function Lion() {
12 this.type = ' Cat ' ;
13 this.size = ' large ' ;
14 }
15
16 let leo = new Lion();
17 // Insert code here
18 leo.roar();
Which two statements could be inserted at line 17 to enable line 18?
A. leo.prototype.roar = () = > { console.log( ' They\ ' re pretty good! ' ); };
B. Object.assign(leo, tony);
C. Object.assign(leo, Tiger);
D. leo.roar = () = > { console.log( ' They\ ' re pretty good! ' ); };
正解：B,D
解説: (Topexam メンバーにのみ表示されます)

質問 5：
What are two unique features of fat-arrow functions compared to normal function definitions?
A. The function receives an argument called parentThis, giving the enclosing lexical scope.
B. If the function has a single expression in the function body, the expression will be evaluated and implicitly returned.
C. The function generates its own this making it useful for separating scope.
D. The function uses the this from the enclosing scope.
正解：B,D
解説: (Topexam メンバーにのみ表示されます)

質問 6：
Refer to the following array:
let arr = [1, 2, 3, 4, 5];
Which two lines of code result in a second array, arr2, created such that arr2 is a reference to arr?
A. let arr2 = arr;
B. let arr2 = arr.slice(0, 5);
C. let arr2 = Array.from(arr);
D. let arr2 = arr.sort();
正解：A,D
解説: (Topexam メンバーにのみ表示されます)

質問 7：
A developer needs to debug a Node.js web server because a runtime error keeps occurring at one of the endpoints.
The developer wants to test the endpoint on a local machine and make the request against a local server to look at the behavior. In the source code, the server.js file will start the server. The developer wants to debug the Node.js server only using the terminal.
Which command can the developer use to open the CLI debugger in their current terminal window?
(With corrected typing errors: node_inspect # node inspect, node_start_inspect # node start inspect.)
A. node inspect server.js
B. node -i server.js
C. node start inspect server.js
D. node server.js --inspect
正解：A