Salesforce CRT-600 問題集

質問 1：
The developer wants to test this code:
Const toNumber =(strOrNum) => strOrNum;
Which two tests are most accurate for this code?
Choose 2 answers
A. console.assert(Number.isNaN(toNumber()));
B. console.assert(toNumber () === NaN);
C. console.assert(toNumber('2') === 2);
D. console.assert(toNumber('-3') < 0);
正解：C,D

質問 2：
is below:
<input type="file" onchange="previewFile()">
<img src="" height="200" alt="Image Preview..."/>
The JavaScript portion is:
01 function previewFile(){
02 const preview = document.querySelector('img');
03 const file = document.querySelector('input[type=file]').files[0];
04 //line 4 code
05 reader.addEventListener("load", () => {
06 preview.src = reader.result;
07 },false);
08 //line 8 code
09 }
In lines 04 and 08, which code allows the user to select an image from their local computer , and to display the image in the browser?
A. 04 const reader = new File();
08 if (file) URL.createObjectURL(file);
B. 04 const reader = new File();
08 if (file) reader.readAsDataURL(file);
C. 04 const reader = new FileReader();
08 if (file) reader.readAsDataURL(file);
D. 04 const reader = new FileReader();
08 if (file) URL.createObjectURL(file);
正解：C

質問 3：
A developer wrote the following code:
01 let X = object.value;
02
03 try {
04 handleObjectValue(X);
05 } catch (error) {
06 handleError(error);
07 }
The developer has a getNextValue function to execute after handleObjectValue(), but does not want to execute getNextValue() if an error occurs.
How can the developer change the code to ensure this behavior?
A. 03 try {
04 handleObjectValue(x)
05 ........................
B. 03 try{
04 handleObjectValue(x);
05 } catch(error){
06 handleError(error);
07 }
08 getNextValue();
C. 03 try{
04 handleObjectValue(x);
05 } catch(error){
06 handleError(error);
07 } then {
08 getNextValue();
09 }
D. 03 try{
04 handleObjectValue(x);
05 } catch(error){
06 handleError(error);
07 } finally {
08 getNextValue();
10 }
正解：A

質問 4：
Given the code below:

What is logged to the console'
A. 2 5 3 4 1
B. 1 2 5 3 4
C. 1 2 3 4 5
D. 2 5 1 3 4
正解：A

質問 5：
Given HTML below:
<div>
<div id ="row-uc"> Universal Container</div>
<div id ="row-aa">Applied Shipping</div>
<div id ="row-bt"> Burlington Textiles </div>
</div>
Which statement adds the priority = account CSS class to the universal Containers row ?
A. Document .querySelector('#row-uc').classes.push('priority-account');
B. Document .querySelector('#row-uc').classList.add('priority-account');
C. Document .querySelectorALL('#row-uc').classList.add('priority-account');
D. Document .queryElementById('row-uc').addclass('priority-account');
正解：D

質問 6：
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 DOM inspector to remove all the elements 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 browser to execute a script that removes all the element containing the class ad-library-item.
正解：A