Brush through the problem, supplement their own shortcomings, consolidate knowledge.

1. The following statements about HTTP requests are incorrectThe radio

  • A. GET requests can be bookmarked
  • B. The LENGTH of GET requests is limited
  • C. The POST request does not require data length
  • D. POST requests can be bookmarked

2. What is not true about the Vue first screen loading optimization?The radio

  • A. Importing components asynchronously improves loading performance
  • B. Introduce view frameworks such as ElementUI as needed
  • C. Reduce the size of the first screen
  • D. Clear the browser cache

3. HTML code representation ().The radio

  • A. Create A table
  • B. Create a scroll menu
  • C. Set the content of each form entry
  • D. Create a drop-down menu

4. <hr noshade>Represents ().The radio

  • A. Indicates that the horizontal line has no shadow
  • B. Indicates that the horizontal line has no border
  • C. There is no shadow on the page border
  • D. Indicates that the horizontal line is not displayed

5. In Vue, when v-for and V-if are used together, which of the following statements is true?The radio

  • A. Execute V-for preferentially
  • B. If v-for and V-if cannot be used at the same time, the execution sequence is not clear and the system crashes
  • C. v-if sets the CSS of the specified element to display: None
  • D. Key in v-for specifies the index parameter of v-for

6. What is the output of this code?The radio

    a();
    function a(){
      console.log(1)}function a(){
      console.log(2)}Copy the code
  • A. 1, 2
  • B. 1
  • C. 2
  • D. Error

7. In JavaScript, the event that fires when an element loses focus is ().The radio

  • A. focus
  • B. unload
  • C. mouseover
  • D. blur

8. What is wrong with JavaScript?The radio

  • A. A scope is A collection of accessible variables, objects, and functions
  • B. A variable is a global variable outside a function
  • C. A variable is not declared in a function and is a local variable
  • D. Local variables operate only inside functions

9. What is wrong with the following statement?The radio

  • A. <s></s>Said superscript
  • B. <strike></strike>Represents the delete line
  • C. <sup></sup>Said superscript
  • D. <u></u>Underscores
Definitions and Usage<s>Tag can be defined plus delete line text definition.<s>The label is<strike>An abbreviated version of the tag, supported by Netscape and Internet Explorer. But it is no longer favored in HTML 4 and XHTML, meaning it is no longer used; It will disappear sooner or later.Copy the code

10. In the SVN version library browser, which command can be used to view logs of the selected file or directory?The radio

  • A. show log
  • B. Rename
  • C. Blame
  • D. Save as

11. The code to open the link in the left frame of the frame page is ().The radio

  • A. <a href=URL target=_top>.. </a>
  • B. <a href=URL target=_left>.. </a>
  • C. <a href=URL target=_self>.. </a>
  • D. <a href=URL target=#left>.. </a>

12. Which of the following events in React is incorrect?The radio

  • A. To address browser compatibility issues, event handling in React is A composite event that acts as A wrapper around cross-browser events and has the same interface as native events
  • B. Use camel name and JSX transfer function as event handler
  • C. Use return false to prevent default behavior
  • D. React does not actually attach events to the child node itself. Instead, it uses a single event listener to listen for all events at the top level through the event delegate mode

React events are synthetic events, not native to the DOM. You can block the default behavior of events by putting false back in the DOM, but React must display the e.preventDefault event object to block the default behavior of events, which is no different from native DOM events

13. CSS3 animation description is incorrectThe radio

  • A. Define the animation using @keyframes
  • B. Animation-play-state Specifies whether the animation is running or paused
  • C. Animation-delay Defines the animation delay time
  • D. Animation-direction Specifies whether the animation will be played in reverse direction in the next cycle. The default property is alternate
The animation-direction property defines whether an animation is played alternately in reverse. Note: This property will not work if the animation is set to play only onceCopy the code
value describe
The default value is normal Press the animation to play normally.
reverse The animation plays in reverse.
alternate Animation in odd number of times (1, 3, 5…) Forward, in even number of times (2, 4, 6…) Play in reverse.
alternate-reverse Animation in odd number of times (1, 3, 5…) Play backwards, in even numbers (2, 4, 6…) Forward play.
initial Set this property to its default value.
inherit Inherits the attribute from the parent element

14. Of the following options, which belong to the union selector writing style is ()The radio

  • A. h1 p{}
  • B. h1_p{}
  • C. h1,p{}
  • D. h1-p{}

15. Which of the following is not a way to communicate between modules in Angular?The radio

  • A. through Service
  • B. use the $rootScope
  • C. Directive Specifies the data binding function
  • D. Modules cannot communicate with each other

16. In React, which lifecycle function can be used to optimize performance?The radio

  • A. shouldComponentUpdate
  • B. componentDidUpdate
  • C. componentWillReceiveProps
  • D. componentWillUpdate
value describe
constructor() React data is initialized. It takes two parameters: props and context. When you want to use these parameters inside a function, you need to pass them in with super(). Note: : Whenever you use constructor() you must write super(), otherwise this will point to an error.
componentWillMount() It is used less often, and more often in server-side rendering. It represents the process when the component has gone through a constructor() initialization of data, but has not yet rendered the DOM.
componentDidMount() When the component is rendered for the first time and the DOM node has been generated, an Ajax request can be called from here and the component will be rendered again after the setState data is returned.
componentWillUnmount() In this step, the component is uninstalled and the data is destroyed, and a parameter nextProps is accepted. By comparing nextProps and this.props, the state of nextProps is changed to the state of the current component, and the component is re-rendered.
componentWillReceiveProps() This is often used when props need to re-render the component after accepting changes to the parent component.
shouldComponentUpdate() Primarily used for performance optimizations (partial updates), only to control the life cycle of component re-rendering, where return False prevents component updates.
componentWillUpdate() ShouldComponentUpdate returns true, the component goes to the rendering process, and goes to componentWillUpdate, where we can also get nextProps and nextState.
componentDidUpdate() React will only enter componentDidmount when it is initialized for the first time, and will enter the life cycle after every re-rendering. PrevProps and prevState are the props and prevState before the update.

17. < body leftmargin =? >Represents the size of the editable area on the left side of the page.The radio

  • correct
  • error

The left margin of the page. The value of # is the distance from the page to the left

18. Display: Inherit After you define it, block-level elements can be displayed in multiple rows.The radio

  • correct
  • error

19. Which of the following statements is true about Webpack?multi-select

  • A. Project internationalization can be configured with the i18N-webpack-plugin
  • B. I18n-webpack-plugin bundles all languages into one bundle
  • C. Webpack can use BannerPlugin to set copyright information
  • D. Webpack can set env’s environment variables using DefinePlugin

20. Please select those with incorrect understanding of javascriptmulti-select

  • A. JScript is short for javascript
  • B. Javascript is a Java scripting language developed by Netscape to simplify Java development
  • C. The main reason for the large number of compatibility problems between FireFox and IE is their different support for javascript
  • D. AJAX technology must use javascript technology

21. Which of the following statements produces a runtime error:The radio

  • A. var obj = (); // Syntax error
  • B. var obj = []; // Create an array
  • C. var obj = {}; // Create an object
  • D. var obj = //;

22. The following statement about tables in HTML is true ().The radio

  • A. In HTML, tables must be defined by<table>Label,<tr>Label,<td>Tag composition, missing any of the tags can be
  • B. How many pairs<td>Tag, how many cells are there
  • C. How many pairs<tr>Tag, how many columns there are
  • D. How many pairs<td>Tag, how many rows

23. What is the function of a key in React?The radio

  • A. In the React Diff algorithm, React uses the Key value of an element to determine whether the element is newly created or moved
  • B. The DOM used to get the element
  • [C]
  • D. Obtain the index value of the current element

24. The following statements about wildcard selectors and combinatorial selectors are trueThe radio

  • A. They can be applied to multiple tags on A page. If there is A conflict between the two styles, use the style in the wildcard selector
  • B. The wildcard selector is suitable for pages with many tags
  • C. In the basic configuration of page style, the combination selector is not suitable for pages with many tags, which will affect the rendering time of the page
  • D. Composition selectors are groups of elements that have the same setting, separated by commas, so that the set style applies to all elements in the group

25. What is not true of the following statementsThe radio

  • A. Streaming layout uses non-fixed pixels to define web content, also known as percentage layout
  • B. Responsive layout Uses media queries in CSS3 to specify a web layout of a width range by querying the width of screen
  • C. Standard flow layout refers to the left to right and top down display of western language text, which is also the familiar layout of text in traditional HTML documents
  • D. Non-standard flow layout refers to the left to right and top down display of western language text, which is also the familiar layout of text in traditional HTML documents

This refers to the left to right and top down display of the Western language text, which is the familiar layout of text in traditional HTML documents. Note that flow directions may differ in non-Western languages. Most elements are in normal flow, and the only way to keep an element out of normal flow is to make it a floating element or a positioning element.

In a standard flow, block-level elements occupy a single row and are placed vertically. Row – level elements are arranged one after the other horizontally.

26. Which of the following are HTML5’s new Input typesThe radio

  • A. email
  • B. hidden
  • C. text
  • D. file

27. What is true of the following statementsThe radio

  • A. CSS auditory style sheets can combine speech composition with sound effects so that users can hear information without reading it
  • B. In the CSS selector[lang|=en]Select all elements whose lang attribute value ends in “en”
  • C. In the CSS selectorp:lang(it)The meaning is to select each with a lang attribute value starting with “it”<p>The element
  • D. CSS selectors:not(p)The meaning of choice is to choose<p>Each element of the element

email url number range Date pickers (date, month, week, time, datetime, datetime-local) search color

28. In HTML, it is used to create a reset button when the type attribute value of the input element in a form is set to ().The radio

  • A. reset
  • B. set
  • C. button
  • D. image

28. The HTML code for the left aligned horizontal line is ().The radio

  • A. <br align=left>
  • B. <tr align=left>
  • C. <hr align=left>
  • D. <hr align=right>

29. The following statements are not true

  • A. Prerequisite for margin merging: margins must be adjacent
  • B. Padding is also called padding. Using padding will change the width and height
  • C. HTML default UL comes with a padding-left
  • D. HTML dl, dt, dd can also be used to build lists

30. To listen for form submissions, which of the following events () should be used.The radio

  • A. onpress
  • B. onclick
  • C. onmouseover
  • D. onsubmit

31. Of the following options, the exact format of the CSS style rule is ().The radio

  • A. Selector {attribute 1: attribute value 1; Attribute 2: Attribute value 2 Attribute 3: Attribute value 3}
  • B. Selector {attribute 1: attribute value 1, attribute 2: attribute value 2, attribute 3: attribute value 3; }
  • C. Selector {attribute 1: attribute value 1; Attribute 2: Attribute value 2; Attribute 3: Attribute value 3; }
  • D. Selector {attribute 1: attribute value 1 Attribute 2: attribute value 2 Attribute 3: attribute value 3}

32. What is true of the following statementsmulti-select

  • One immediate benefit of HTML code compression is that it reduces the size of HTML pages to increase front-end loading speed
  • B. HTML code is compressed by removing comment marks, newlines, Spaces, tabs, and so on
  • C. CSS file code compression can reduce the size of external CSS files
  • D. HTML code obfuscation does not have any impact on performance

33. Which of the following are new features of HTML5multi-select

  • A. Local offline storage
  • B. Better semantic content elements
  • C. CSS auditory style sheets
  • D. Add labels such as font and header

33. What is true about the Windows object in IEmulti-select

  • The a. window.opener property itself points to the window object
  • The b.window.reload () method can be used to refresh the current page
  • C. window.location= “a.html” and window.location.href= “A.html” both replace the current page with a.html
  • D. Global variable g is defined; This variable can be accessed as window.g

34. What is true about CSS is:The radio

  • A. The margin value can be negative, and the padding value cannot
  • B. Setting width or height for inline elements also works
  • C. Use the CSS<div></div>Carry out structural design
  • D. Margin You can set the background color separately

35. Which directory is not included in the default directory of the Vue project?The radio

  • A. config
  • B. src
  • C. static
  • D. view

36. What is wrong about Set structure and WeakSet structure?The radio

  • A. All structure members in Set are unique and cannot be repeated
  • B. A Set can be initialized to accept an array as an argument
  • C. WeakSet cannot be traversed
  • D. WeakSet members are not unique and can be repeated
A Set allows you to store unique values of any type, whether primitive or object references. A Set is a collection of values, and you can iterate over its elements in the order in which they were inserted. The element in the Set will only appear once, that is, the element in the Set is unique. WeakSet object is a collection of object values, and each object value in it can only appear once. In the Set of WeakSet is the only WeakSet appears mainly to solve the weak reference object storage scene, its structure and Set similar to the difference between Set and Set compared with Set, WeakSet can only be a collection of objects, but not any type of arbitrary value WeakSet object reference for weak reference. If there are no other references to WeakSet objects, those objects will be garbage collected. This also means that WeakSet does not store a list of current objects. Because of this, WeakSet is not enumerable. The properties of WeakSet are consistent with the operation method and Set. The difference is that WeakSet has no traversal method, because its members are weak references, and weak references will disappear at any time. Traversal mechanism cannot guarantee the existence of members Set, Map, WeakSet, WeakMap, are all a Set of data structure Set, WeakSet is [value, value] Set, and has a unique Map and WeakMap is a Set of [key, value], Map key can be any type, The key of WeakMap can only be the object type Set and Map with traversal method. WeakSet and WeakMap belong to weak reference and cannot be traversalCopy the code

JavaScript is an event-driven language.The radio

  • A. right
  • B. errors

38. How to solve the problem of style compatibility between different browsers?multi-select

  • A. After determining the cause of the problem and the troubled browser, use A separate style sheet that can only be loaded by the troubled browser. This approach requires the use of server-side rendering
  • B. Use Autoprefixer to automatically generate CSS property prefixes
  • C. Use Reset CSS or normalize.css
  • D. Use libraries that already handle such issues

38. In Vue, which of the following attributes is not proxied by a Vue instance?multi-select

  • A. $item1
  • B. item2
  • C. 3item
  • D. _item4

Attributes beginning with _ or $will not be propped by Vue instances because they may conflict with Vue built-in attributes and API methods.