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2021 Yahong pen test questions

2022-07-28 16:02:00 【PBitW】

List of articles

After the element floats ,display What is it? ？
- 1、block
- 2、 unchanged
Which of the following is not canvas Methods
No input stay html5 The new type of
p.list pan and p:last-child span Whose weight is high
["1","2","3"].map(parseInt)
Yes http Incorrect statement
Code running problem
hasOwnProperty and set.has

After the element floats ,display What is it? ？

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This is usually not noticed , Not at all . I usually think , This is out of the document flow , So the width doesn't seem to take up all , That should be D 了 .

But see code ：

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style> div{
       float: left; } </style>
</head>
<body>
  <div>
    <p> This is a div Inside p</p>
  </div>
  <span style="float: right;">
    aaaa<span> This is a div Inside p</span>aaa
  </span>
  <span style="float: right;display: inline-block;">
    aaaa<span> This is a div Inside p</span>aaa
  </span>
  <p> This is a p</p>
</body>
</html>

The rookie found something wrong

1、block

The first two are not set display, Then the result after running , All are ：
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Be careful ：

span Only here , stay style There is no display Of this property ！

2、 unchanged

But the third one , I set it myself display, Although the settings are still displayed here display
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But the difference is style Inside

What is this block Or unchanged ？

Anyway, what the rookie found is what he said block,https://www.cnblogs.com/lmy-ms/p/6425504.html

Which of the following is not canvas Methods

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This pair canvas Students who learn well should not be a problem , Anyway, I don't think I've met you in my usual project canvas, At most echarts yes canvas Written ！

Students who don't know can watch ：https://www.runoob.com/w3cnote/html5-canvas-intro.html

No input stay html5 The new type of

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Cough cough cough , The novice is wrong about this question , Should be B (file), Others are new , Here you can see the blog written by the novice ：https://blog.csdn.net/langwang_100/article/details/107515920 , Anyway, rookies feel so much , I can't remember , Just search it when you use it ？

p.list pan and p:last-child span Whose weight is high

The novice forgot the content of his blog when taking the exam , Come back and have a look , Fortunately, I chose the right one
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Priority relation ： inline style > ID Selectors > Class selectors = Attribute selector = Pseudo class selector > tag chooser = Pseudo element selector

See my blog for details ：
https://blog.csdn.net/langwang_100/article/details/107768098
https://blog.csdn.net/langwang_100/article/details/108206686

[“1”,“2”,“3”].map(parseInt)

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reason ：

Be careful ：

there index Represents the subscript of the array ,array Is the array itself ！

Reference documents ：
Array.prototype.map() Documents

Yes http Incorrect statement

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The answer is A, Tell the truth , Who can remember so many numbers , I know about it 1–> Information ,2–> success ,3–> Redirect ,4–> Client error ,5–> Server error ,

For details, see ：https://www.runoob.com/tags/html-httpmessages.html

B,C See you for the answer ：
https://blog.csdn.net/qq_32534441/article/details/89639266
https://blog.csdn.net/weixin_42164539/article/details/104716843
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D The rookie originally thought https Very complicated , It turned out to be http Encrypted ！

Code running problem

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In fact, this problem is a simple problem of variable assignment and scope , because catch Yes. x, So when assigning values in functions , What is assigned is a local variable x, Not the outside x, So there is no way to visit outside , So outside x still undefined, And inside y Because it is assigned , So when printing 2！