This is the 9th day of my participation in the August More Text Challenge

☆☆☆ Today’s content (using functions to achieve specific functions) is important!! Is also the most basic ability requirements! Do do do

Can serve as a beginner’s learning route, can refer to, learning progress is not particularly driven! Keep updating,

With their own understanding, simple and comprehensive summary of the basic knowledge points, most of the content for the vernacular content, the foundation of the foundation of the foundation to deepen understanding!

Consolidate the basic knowledge of learning JavaScript, deepen the understanding of memory, to build a solid foundation to high-rise! Come on

For more details on learning – recommended view MDN-JavaScript documentation, (little Red Book/white paper/blue book /..) Learn to advance!

Read more: Review of previous updates

【 Relearn JS】 Study every day to consolidate the foundation: 【 Day1 】

【 DAY2 】, 【day3】, 【day4】, 【day5】, 【day6】, 【day7】, 【day8】,

☆☆☆ Today’s content is more important, but also the most basic ability requirements in the work! Do do do

Let’s get started! Take each day seriously!!

1, comb the knowledge learned yesterday

  • Array deduplicating:

  • Plan 2: Order the array 1 1 1 33 33 55 66 100

    If the previous number! = the last number is stored in the array 1, 33, 55, 66, 100

for (var i = 0; i < arr.length; i++) {
  if(arr[i] ! = arr[i +1]) {
    brr.push(arr[i])
  }
}
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  • Sorting:Bubble sort       Selective sorting
sort(function (a, b) {
  return a - b
})
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  • You can add an array using forEach indexOf Map filter reduce

  • String object:

    • CharAt ()   charCodeAt    String.fromCharCode
    • indexOf   lastIndexOf
    • substr substring
    • split
    • replace
    • trim
    • toLowerCase

2,MathObject mathematical object

Note: The Math object does not need to be defined to invoke methods directly in math. mode

2.1 Three methods of rounding:

  • Math.floor(m) round down math.floor (4.9) 4 math.floor (-4.9) -5 to get the largest integer less than m

  • Math.ceil(m) rounding math.ceil (4.3) 5 Math.ceil(-4.3) -4 yields the smallest integer greater than m

  • Math.round(m) Round math.round (4.5) 5

  • Math.abs(m) takes the absolute value

  • Math.pow(m,n) gets m to the NTH power

  • Math. SQRT (m) to take root

  • Math.max(multiple numbers) takes the maximum value

  • Math. Min () the minimum value

  • Math.min.apply(null, []) gets the minimum value of the array

  • Math.max.apply(null, []) gets the maximum value of the array

  • Math.random() gets a random decimal between [0,1)

To obtain any interval value formula:

Math.round(Math.random() * (max - min) + min)
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Package function functions:

Define a function to get arbitrary interval value data:

function rand(min,max){
  return  Math.round( Math.random()_(max-min) + min )
}
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3,Dateobject

Definition:

var d = new Date(); Gets the current system time

  • toLocaleString() Convert the date to local time format
  • getFullYear() for years
  • getMonth() month gets 0–11 using d.goetmonth () + 1
  • getDate(),
  • getHours() hours
  • getMinutes()
  • getSeconds() seconds
  • getDay()Week 0- 60 0 indicates Sunday

Write a function functiondateToString()

4.1 Function Display a customized date and time format

function dateToString(now) {
  var str1 = now.getFullYear() + The '-' + (now.getMonth() + 1) + The '-' + now.getDate()
  var h = toTwo(now.getHours())
  var m = toTwo(now.getMinutes())
  var s = toTwo(now.getSeconds())

  var str2 = h + ':' + m + ':' + s

  return str1 + ' ' + str2
}
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4.2 Functions Functions0Fill a

The function checks whether the passed parameter is less than 10. If less than 10, concatenate 0 in front of the number

function toTwo(num) {
  // Returns a two-digit number
  return num < 10 ? '0' + num : num
}
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5, custom time format

There are no hours and seconds. The default is 8 a.m

var d = new Date('1998-09-09')
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6, write a function:stringToDate()  

The date () function converts a string to a date

function stringToDate(str) {
  return new Date(str)
}
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7. Time difference:getTime()  

The now () function returns the milliseconds between midnight, 1970.1.1 and now

Time difference function

function diff(start, end) {
  // Returns the time difference in seconds
  return Math.abs(start.getTime() - end.getTime()) / 1000
}
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8. Set the timesetDate()

Set the time a few days later

SetDate (current date + number of days) The setDate() method changes

The result of the original day object

Such as:

var now = new Date(a)// Set the time after 9 days
now.setDate(now.getDate() + 9)
alert(now)
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SetTime () usage:

Date object.setTime (current date ms value + number of days * 1000 * 3600 * 24)

9. TimersetInterval

  • Definition:
var timer = setInterval(Tasks to be performed, interval time)// Time default: milliseconds
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The typical task to perform is a function function

  • Clear timer:

ClearInterval (Timer name);

Come on, dream chaser

Learning is a continuous process, stick to it, there will be harvest!

Accumulate over a long period, consolidate the foundation, early into Dachang!

It’s not easy to keep it up, and it’s not easy to keep it up. You’re great!

Calm Down & Carry On!