Salesforce JavaScript-Developer-I 問題集

質問 1：
A developer at Universal Containers is creating their new landing pagebased on HTML, CSS, and JavaScript.
The website includes multiple external resources that are loaded when the page is opened.
To ensure that visitors have a good experience, a script named personalizeWebsiteContent needs to be executed when the webpage isloaded and there is no need to wait for the resources to be available.
Which statement should be used to call personalizeWebsiteContent based on the above business requirement?
A. windows,addEventListener('onload', personalizeWebsiteContent);
B. windows,addEventListener('load', personalizeWebsiteContent);
C. windows,addEventListener('DOMContent Loaded ', personalizeWebsiteContent);
D. windows,addEventListener('onDOMCContentLoaded', personalizeWebsiteContent);
正解：B

質問 2：
A developer is debugging a web server that uses Node.js The server hits a runtimeerror every third request to an important endpoint on the web server.
The developer added a break point to the start script, that is at index.js at he root of the server's source code. The developer wants to make use of chrome DevTools to debug.
Which command can be run to access DevTools and make sure the breakdown is hit ?
A. Node --inspect index.js
B. node -i index.js
C. Node --inspect-brk index.js
D. Node inspect index.js
正解：A

質問 3：
Refer to the code below:
01 let car1 = new promise((_, reject) =>
02 setTimeout(reject, 2000, "Car 1 crashed in"));
03 let car2 = new Promise(resolve => setTimeout(resolve, 1500, "Car 2
completed"));
04 let car3 = new Promise(resolve => setTimeout (resolve, 3000, "Car 3
Completed"));
05 Promise.race([car1, car2, car3])
06 .then(value => (
07 let result = $(value) the race. `;
08 ))
09 .catch( arr => (
10 console.log("Race is cancelled.", err);
11 ));
What is the value of result when Promise.race executes?
A. Race is cancelled.
B. Car 2 completed the race.
C. Car 3 completed the race.
D. Car 1 crashed in the race.
正解：B

質問 4：
Given the code below:
Which three code segments result in a correct conversion from number to string? Choose 3 answers
A. let scrValue = String(numValue);
B. let strValue = * * 4 numValue;
C. let strValue = (String)numValue;
D. let strValue = numValue. toString();
E. let strValue = numValue.toText ();
正解：A,B,D

質問 5：
Considering type coercion, what does the following expression evaluate to?
True + '13' + NaN
A. ' 113Nan '
B. ' true13 '
C. 14
D. ' true13NaN '
正解：D

質問 6：
A developer is asked to fix some bugs reported by users. To do that, the developer adds abreakpoint for debugging.
Function Car (maxSpeed, color){
This.maxspeed =masSpeed;
This.color = color;
Let carSpeed = document.getElementById(' CarSpeed');
Debugger;
Let fourWheels =new Car (carSpeed.value, 'red');
When the code execution stops at the breakpoint on line 06, which two types of information are available in the browser console ?
Choose 2 answers:
A. The style, event listeners and other attributes applied to the carSpeed DOM element
B. The values of the carSpeed and fourWheels variables
C. A variable displaying the number of instances created for the Car Object.
D. The information stored in the window.localStorage property
正解：A,D

質問 7：
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 replaceline 01 and declare the function for use?
Choose 2 answers
A. const log = (logInput) => {
B. function log = (logInput) {
C. const log(loginInput) {
D. function leg(logInput) {
正解：A,D

質問 8：
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 insidethe 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 DOM inspector to remove all the elements containing the class ad-library-item.
B. Use the browser console to execute a scriptthat prevents the load event to be fired.
C. Use the DOM inspector to prevent the load eventto be fired.
D. Use the browser to execute a script that removes all the element containing the class ad-library-item.
正解：D

質問 9：
A developer initiates a server with the file server,js and adds dependencies in the source codes package,json that are required to run the server.
Which command should the developer run to start the server locally?
A. node start
B. npm start server,js
C. npm start
D. start server,js
正解：C