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JS question brushing exercise - niuke.com

2022-07-19 14:26:00 【Front end Xiaobai is moving forward】

During this period of time, some friends are asking if there is any good question brushing website
Here I recommend a question brushing website Click to visit Niuke
Niuke supports the learning of multiple programming languages , Interview questions of major Internet companies , From foundation to elevation , Come and experience it ！

introduction

Some time ago, I wanted to find some websites to improve js level , Inadvertently enter Niuke network , Niuke network has front-end html、css、js Exercises , Basic , Have high , Today I'm going to practice , I think Niuke has many advantages ：
The code is easy to debug , It is also very convenient to run
The page is relatively simple , There's not so much fancy
The overall quality of the exercise questions is good

Front end interviewer tears questions

Event delegation

describe
Please complete it JavaScript Code , Requirements are as follows ：
to "ul" Add click event to tag
When clicking on a "li" When labeling , The label content is spliced ".“ Symbol . Such as ： some "li" When the tag is clicked , The label reads ”…"
Be careful ： You have to use DOM0 Level standard event （onclick）

<!DOCTYPE html>
<html>
    <head>
        <meta charset=utf-8>
    </head>
    <body>
    	<ul>
            <li>.</li>
            <li>.</li>
            <li>.</li>
        </ul>

        <script type="text/javascript"> //  The completion code  </script>
    </body>
</html>

My answer :

            document.querySelector('ul').onclick = function(event) {
    
                event.target.innerText += '.'
            }

analysis :

This question is about basic knowledge ,target Express Currently triggered events , By selecting the parent element ul, Then the event agent , Then we get the answer

Array weight removal

describe
Please complete it JavaScript Code , It is required to remove the duplicate numeric items in the array parameters and return the array .
Be careful ： Array elements contain only numbers

Example 1

Input ：_deleteRepeat([-1,1,2,2])
Output ：[-1,1,2]

<!DOCTYPE html>
<html>
    <head>
        <meta charset=utf-8>
    </head>
    <body>
    	
        <script type="text/javascript"> const _deleteRepeat = array => {
       //  The completion code  } </script>
    </body>
</html>

My answer :

		<script type="text/javascript">
            const _deleteRepeat = array => {
    
                //  The completion code 
                return [...new Set(array)]
            }
        </script>

analysis :

This problem can be said to be completely for nothing ,es6 Medium set Collection can be easily solved ,set The collection has the function of automatic de duplication ,es6 Knowledge is detailed in es6 Knowledge summary

Quick sort

describe
Please complete it JavaScript Code , It is required to sort the numbers in the array parameters from small to large and return the array .
Be careful ：1. Array elements contain only numbers
2. Please use the quick sort method first

Example :

Input : _quickSort([0,-1,1,-2,2])
Output ：[-2,-1,0,1,2]

<!DOCTYPE html>
<html>
    <head>
        <meta charset=utf-8>
    </head>
    <body>
    	
        <script type="text/javascript"> const _quickSort = array => {
       //  The completion code  } </script>
    </body>
</html>

My answer :

		<script type="text/javascript">
            const _quickSort = array => {
    
                //  The completion code 
                array.sort((a,b)=>{
    
                    return a-b
                })
                return array
            }
        </script>

analysis :

In fact, this problem is not difficult , Array sort Method to sort , however sort Method defaults to unicode code Sequential arrangement , Here you pass in a function , Implement sorting from small to large ,sort See the article for details js in sort() Detailed explanation of the method

Summary

While learning knowledge , We must always come back and do some review , Only in this way can we make progress , Practicing exercises can help us consolidate our knowledge , Niuke is worth brushing questions to improve yourself ！

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