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The main content of this article is to explain "what is a very practical JavaScript line of code", interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Now let the editor to take you to learn "what are the very practical JavaScript lines of code?"

I. date processing

1. Check whether the date is valid

This method is used to detect whether the given date is valid:

Const isDateValid = (... val) = >! Number.isNaN (new Date (.. Val). ValueOf (); isDateValid ("December 17, 1995 03:24:00"); / / true

two。 Calculate the interval between two dates

This method is used to calculate the interval between two dates:

Const dayDif = (date1, date2) = > Math.ceil (Math.abs (date1.getTime ()-date2.getTime ()) / 86400000) dayDif (new Date ("2021-11-3"), new Date ("2022-2-1") / / 90

3. The date of the search is on the day of the year.

This method is used to detect that the given date is located on the day of this year:

Const dayOfYear = (date) = > Math.floor ((date-new Date (date.getFullYear (), 0,0)) / 1000 / 60 / 60 / 24); dayOfYear (new Date ())

2021 has passed.

4. Time formatting

This method can be used to convert time to hour:minutes:seconds format:

Const timeFromDate = date = > date.toTimeString (). Slice (0,8); timeFromDate (new Date (2021, 11, 2, 12, 30, 0)); / / 12:30:00timeFromDate (new Date ()); / / returns the current time at 09:00:00

Second, string processing

1. The first letter of a string is capitalized

This method is used to capitalize the first letter of an English string:

Const capitalize = str = > str.charAt (0). ToUpperCase () + str.slice (1) capitalize ("hello world") / / Hello world

two。 Flip a string

This method is used to flip a string and return the flipped string:

Const reverse = str = > str.split (''). Reverse (). Join (''); reverse ('hello world'); / /' dlrow olleh'

3. Random string

This method is used to generate a random string:

Const randomString = () = > Math.random (). ToString (36) .slice (2); randomString ()

4. Truncate string

This method truncates the string from the specified length:

Const truncateString = (string, length) = > string.length

< length ? string : `${string.slice(0, length - 3)}...`;truncateString('Hi, I should be truncated because I am too loooong!', 36) // 'Hi, I should be truncated because...' 5. 去除字符串中的HTML 该方法用于去除字符串中的HTML元素： const stripHtml = html =>

(new DOMParser () .parseFromString (html, 'text/html')) .body.textContent | |''

3. Array processing

1. Remove duplicates from the array

This method is used to remove duplicates from the array:

Const removeDuplicates = (arr) = > [. New Set (arr)]; console.log (removeDuplicates ([1, 2, 2, 3, 3, 4, 4, 5, 5, 6])

two。 Determine whether the array is empty

This method is used to determine whether an array is empty, and it returns a Boolean value:

Const isNotEmpty = arr = > Array.isArray (arr) & & arr.length > 0terisNotEmpty ([1,2,3]); / / true

3. Merge two arrays

You can merge two arrays using the following two methods:

Const merge = (a, b) = > a.concat (b); const merge = (a, b) = > [... a,... b]

IV. Digital operation

1. Judge whether a number is odd or even

This method is used to determine whether a number is odd or even:

Const isEven = num = > num% 2 = = 0nterisEven

two。 Get the average of a set of numbers

Const average = (... args) = > args.reduce ((a, b) = > a + b) / args.length;average (1,2,3,4,5); / / 3

3. Get a random integer between two integers

This method is used to obtain random integers between two integers.

Const random = (min, max) = > Math.floor (Math.random () * (max-min + 1) + min); random (1,50)

4. The specified number of digits is rounded

This method is used to round a number to finger positioning:

Const round = (n, d) = > Number (Math.round (n + "e" + d) + "e -" + d) round (1.005, 2) / / 1.01round (1.555, 2) / / 1.56

Fifth, color operation

1. Convert RGB to sixteen mechanisms

This method converts the color value of a RGB to a hexadecimal value:

Const rgbToHex = (r, g, b) = > "#" + ((1 [xss_clean] = cookie.replace (/ ^ + /,'). Replace (/ =. * /, `=; expires=$ {new Date (0). ToUTCString ()}; path=/`)

3. Get the selected text

This method gets the text selected by the user through the built-in getSelection attribute:

Const getSelectedText = () = > window.getSelection (). ToString (); getSelectedText ()

4. Detect if it is in dark mode

This method is used to detect whether the current environment is in dark mode, which is a Boolean value:

Const isDarkMode = window.matchMedia & & window.matchMedia ('(prefers-color-scheme: dark)') .matchesconsole.log (isDarkMode)

5. Scroll to the top of the page

This method is used to return to the top of the page:

Const goToTop = () = > window.scrollTo (0,0); goToTop ()

6. Determine whether the current tab is active

This method is used to detect whether the current tab has been activated:

Const isTabInView = () = >! document.hidden

7. Determine whether it is currently an Apple device

This method is used to detect whether the current device is an Apple device:

Const isAppleDevice = () = > / Mac | iPod | iPhone | iPad/.test (navigator.platform); isAppleDevice ()

8. Whether to scroll to the bottom of the page

This method is used to determine whether the page has been at the bottom:

Const scrolledToBottom = () = > document.documentElement.clientHeight + window.scrollY > = document.documentElement.scrollHeight

9. Redirect to a URL

This method is used to redirect to a new URL:

Const redirect = url = > location.href = urlredirect ("https://www.google.com/")

10. Open the browser print box

This method is used to open the print box of the browser:

Const showPrintDialog = () > window.print ()

VII. Other operations

1. Random Boolean value

This method can return a random Boolean value, and a random number of 0-1 can be obtained by using Math.random (). Compared with 0. 5, there is a 50% chance of getting a true or false value.

Const randomBoolean = () = > Math.random () > = 0.5 investors Boolean ()

two。 Variable exchange

You can use the following form to exchange the values of two variables without the application of the third variable:

[foo, bar] = [bar, foo]

3. Get the type of variable

This method is used to get the type of a variable:

Const trueTypeOf = (obj) = > Object.prototype.toString.call (obj) .slice (8,-1). ToLowerCase (); trueTypeOf (''); / / stringtrueTypeOf (0); / / numbertrueTypeOf (); / / undefinedtrueTypeOf (null); / / nulltrueTypeOf ({}); / / objecttrueTypeOf ([]); / / arraytrueTypeOf (0); / / numbertrueTypeOf () = > {}); / / function

4. The conversion between Fahrenheit and Celsius

This method is used for the conversion between degrees Celsius and Fahrenheit:

Const celsiusToFahrenheit = (celsius) = > celsius * 9 to 5 + 32 to Const fahrenheitToCelsius = (fahrenheit) = > (fahrenheit-32) * 5 to 9 / celsiusToFahrenheit (15); / / 59celsiusToFahrenheit (0); / / 32celsiusToFahrenheit (- 20); / /-4fahrenheitToCelsius (59); / / 15fahrenheitToCelsius (32); / / 0

5. Check whether the object is empty

This method is used to detect whether a JavaScript object is empty:

Const isEmpty = obj = > Reflect.ownKeys (obj). Length = = 0 & & obj.constructor = Object; so far, I believe you have a deeper understanding of "what is a very practical line of JavaScript code?" you might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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