ES6 Tutorial - String, Function Parameters, Understanding Function's arguments Object, js Object-Oriented, Design Pattern - Singleton Pattern, Deconstruction Assignment

Preface

This paper mainly explains ES6's expansion of strings, including include, start with and end with, and adds a string template.

Start

Does include () include
What does startsWith() begin with?
What does endsWith() end with?

<!DOCTYPE html>
<html>
<head>
 <meta charset="UTF-8">
 <title>ES6-Character string</title>
</head>
<body>
 <script>
   let str = "Why are you here all the time?";
   let res = str.includes('One');
   console.log(res);
 </script>
</body>
</html>

Returns true

<!DOCTYPE html>
<html>
<head>
 <meta charset="UTF-8">
 <title>ES6-Character string</title>
</head>
<body>
 <script>
   let str = "Why are you here all the time?";
   let res = str.startsWith('you');
   console.log(res);
 </script>
</body>
</html>

Returns true

<!DOCTYPE html>
<html>
<head>
 <meta charset="UTF-8">
 <title>ES6-Character string</title>
</head>
<body>
 <script>
   let str = "Why are you here all the time?";
   let res = str.startsWith('you');
   if(str.startsWith('you')){
     Execution statement;
   }else if(Sentence){
     Execution statement;
   }else{  
     Execution statement;
   }
 </script>
</body>
</html>

str.endsWith();

<!DOCTYPE html>
<html>
<head>
 <meta charset="UTF-8">
 <title>ES6-Character string</title>
</head>
<body>
 <script>
   let str = "Why are you here all the time?";
   alert( str.endsWith('this'));
 </script>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
 <meta charset="UTF-8">
 <title>ES6-Character string</title>
</head>
<body>
 <script>
   let mail = '34234@qq.com';
  
   if( mail.endsWith('@qq.com') || main.endsWith('@163.com') ){
      alert('Input correct');
    }else{
      alert('Please enter your mailbox');
    }
 </script>
</body>
</html>

String template

<!DOCTYPE html>
<html>
<head>
 <meta charset="UTF-8">
 <title>ES6-Character string</title>
</head>
<body>
 <script>
   let str2 = `
               <ul>
                 <li>content</li>
               </ul>
               `;
    console.log(str2);
 </script>
</body>
</html>

Parameters of functions

Function parameters, expansion operator:...

<!DOCTYPE html>
<html>
<head>
 <meta charset="UTF-8">
 <title>ES6-Function parameter</title>
</head>
<body>
 <script>
  function fun(a,b){
    console.log(a,b);
  }
 
  fun(1,2);
 </script>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
 <meta charset="UTF-8">
 <title>ES6-Function parameter</title>
</head>
<body>
 <script>
  function fun(a,b,...args){
    console.log(a,b);
    console.log(...args);
  }
  fun(1,2,3,4,5);
  fun(1,2);
 </script>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
 <meta charset="UTF-8">
 <title>ES6-Function parameter</title>
</head>
<body>
 <script>
  let arr = [1,2,3];
  function fun(a,b,c){
   console.log(a);
   console.log(b);
   console.log(c);
  }
  fun(arr[0],arr[1],arr[2]);
  fun(...arr);
 </script>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
 <meta charset="UTF-8">
 <title>ES6-Function parameter</title>
</head>
<body>
 <script>
  let arr = [1,2,3];
  let arr1=[4,5,6];
  let array=[...arr,...arr1];
  console.log(array);
 </script>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
 <meta charset="UTF-8">
 <title>ES6-Function parameter</title>
</head>
<body>
 <script>
  function fun(a=1,b=2,c=3){
   console.log(a,b,c);
  }
  fun();
  // fun(4,5,6);
 </script>
</body>
</html>

arguments object for understanding functions

arguments is an object, an array of classes

<!DOCTYPE html>
<html>
<head>
 <meta charset="UTF-8">
 <title>Document</title>
</head>
<body>
 <script>
   function add(a,b){
    return a+b;
   }
   console.log(add(1,2);
 </script>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
 <meta charset="UTF-8">
 <title>Document</title>
</head>
<body>
 <script>
   function add(){
    // Console. log (arguments); // return object
    return arguments[0] + arguments[1];
   }
   add(1,2);
   console.log( add(1,2) );
 </script>
</body>
</html>

js object-oriented

// var student = {}; // create objects
var student = new Object();
student.name = "dashu";
student.age = 12;
student.job = "school student";
student.study = function(){
 alert("study");
}
student.study();

var student = {
 name : "dashu",
 age : 12;
 job: "school student",
 study : function(){
  alert("study");
  }
};
student.study();

In data attribute js

var student = {
 name: "dashucoding"
}
alert(student.name);

var student={};
Object.defineProperty(student,"name",{
 writable:true,
 value: "dashucoding"
});
alert(student.name);

configurable indicates whether attribute values can be deleted by delete, which defaults to true
Enumerable indicates whether the attribute values of an object can be enumerated by for-in, which defaults to true
Wtable indicates whether the attribute value can be modified by default to true

Design Patterns - Singleton Patterns

var mask = function(){
 document.body.appendChild(document.createElement('div'));
}
var obtn = document.getElemetnById("btn");
obtn.onclick = function(){
 mask();
}

// Singleton mode
var singleton = function(){
 var res;
 return function(fn){
  return res||(res=fn.apply(this,arguments))
 }
}();
var obtn = document.getElementById("btn");
obtn.onclick=function(){
 singleton(function(){
  return document.body.appendChild(document.createEelement('div'));
 })
}

Destructuring assignment

Deconstruction assignment is an expression used to obtain data

let arr=[1,2,3];
let a = arr[0];
let b = arr[1];
let c = arr[2];
console.log(a,b,c);

let arr = [1,2,3];
let [a,b,c] = arr;
console.log(a,b,c);

let arr = {
 a:1,
 b:2,
 c:3
}
let (a,b,c) = arr;
// let(a,b,c) = [1,2,3];
console(a,b,c);

epilogue

This article mainly explains ES6 tutorial - string, function parameters, arguments object, js object-oriented, design pattern - singleton pattern, deconstruction assignment.
Next, I will continue to explain other knowledge in depth. I am interested in continuing to pay attention to it.
A little gift or a little compliment

Posted by mrausch on Mon, 04 Feb 2019 10:51:16 -0800

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