JavaScript で配列から重複を削除する

このチュートリアルでは、setオブジェクト、forループ、filter()を使用して、JavaScriptの配列から重複を削除する方法をいくつか学びます。

JavaScriptは配列から重複を削除します

配列から重複を削除するには、次のjavascript配列メソッドを1つずつ参照してください。

  • 1:SetObjectを使用してJavaScriptの配列から重複を削除する方法
  • 2:Array.filter()メソッドを使用して配列javascriptから重複を削除するには
  • 3:foreachループを使用して配列javascriptから重複を削除するには

1:SetObjectを使用してJavaScriptの配列から重複を削除する方法

setオブジェクトを使用して、javascriptの配列から重複を削除できます。

構文

new Set([value]);

注: –値–パラメーターが指定されていないか、nullが渡された場合、作成された新しいセットは空です。
 

例1:-SetObjectメソッドの使用

javascriptに数値配列があり、重複する要素が含まれています。setオブジェクトを使用して、javascriptの配列から重複する数値を削除できます。以下の例を見ることができます:

var number = [1, 2, 1, 3, 4, 5, 2, 6, 3, 4];
 
var unique = [...new Set(number)];
 
document.write( "Output :- " + unique ); 
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>javascript remove duplicate numbers from array</title>
</head>
<body>
  <script type = "text/javascript">
     
    var number = [1, 2, 1, 3, 4, 5, 2, 6, 3, 4];
 
    var unique = [...new Set(number)];
   
    document.write( "Output :- " + unique ); 
 
  </script>  
</body>
</html>

上記のコードの結果は次のとおりです。出力:-1,2,3,4,5,6

2:Array.filter()メソッドを使用して配列javascriptから重複を削除するには

javascript配列filter()およびindexof()メソッドを使用して、javascriptの配列から重複する要素または値を削除できます。

フィルタメソッドの構文:

array.filter(function(currentValue、index、arr)、thisValue)

例1:-Array.filter() メソッドの使用 

 

var number = [1, 2, 1, 3, 4, 5, 2, 6, 3, 4];
 
var x = (number) => number.filter((v,i) => number.indexOf(v) === i)
 
document.write( "Output :- " + x(number) ); 
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>javascript remove duplicate elements or values from array using filter() function</title>
</head>
<body>
  <script type = "text/javascript">
     
    var number = [1, 2, 1, 3, 4, 5, 2, 6, 3, 4];
 
    var x = (number) => number.filter((v,i) => number.indexOf(v) === i)
   
    document.write( "Output :- " + x(number) ); 
 
  </script>  
</body>
</html>

上記のコードの結果は次のとおりです。出力:-1,2,3,4,5,6

例2:-javascriptフィルターmethod()の使用

javascriptに重複する値を持つ配列があります。また、JavaScriptの文字列配列から重複する要素または値を削除する場合。したがって、以下の例を使用できます。

var array = ['John','Make','Mac', 'David', 'Smith', 'John', 'Mac', 'Make']
var filterArray = array.filter(function(item, index){
     return array.indexOf(item) >= index;
 });
 
 document.write( "Output :- " + filterArray ); 

 

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>JavaScript Remove duplicate elements from string array</title>
</head>
<body>
  <script type = "text/javascript">
     
    var array = ['John','Make','Mac', 'David', 'Smith', 'John', 'Mac', 'Make']
    var filterArray = array.filter(function(item, index){
        return array.indexOf(item) >= index;
    });
   
    document.write( "Output :- " + filterArray ); 
 
  </script>  
</body>
</html>

上記のコードの結果は次のとおりです。出力:-John、Make、Mac、David、Smith

3:foreachループを使用して配列javascriptから重複を削除するには

javascriptのarray.forEachメソッドを使用して、重複する値または要素を配列から削除できます。

構文

 array.forEach(function(currentValue、index、arr)、thisValue);

例1:-forEach()メソッドの使用

forEachを使用して配列javascriptから重複を削除する例を見ることができます。

var number = [1, 2, 1, 3, 4, 5, 2, 6, 3, 4];
 
function removeDuplicateFromArray(number) {
  var uniqueVal = {};
  number.forEach(function(i) {
    if(!uniqueVal[i]) {
      uniqueVal[i] = true;
    }
  });
  return Object.keys(uniqueVal);
}
 
document.write( "Output :- " + removeDuplicateFromArray(number) ); 
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Using foreach method of javascript, to remove duplicate elements or values from array</title>
</head>
<body>
  <script type = "text/javascript">
     
    var number = [1, 2, 1, 3, 4, 5, 2, 6, 3, 4];
 
    function removeDuplicateFromArray(number) {
      var uniqueVal = {};
      number.forEach(function(i) {
        if(!uniqueVal[i]) {
          uniqueVal[i] = true;
        }
      });
      return Object.keys(uniqueVal);
    }
   
    document.write( "Output :- " + removeDuplicateFromArray(number) ); 
 
  </script>  
</body>
</html>

上記のコードの結果は次のとおりです。出力:-1,2,3,4,5,6

リンク: https://www.tutsmake.com/javascript-remove-duplicates-from-array/

#javascript 

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JavaScript で配列から重複を削除する

Rahul Jangid

1622207074

What is JavaScript - Stackfindover - Blog

Who invented JavaScript, how it works, as we have given information about Programming language in our previous article ( What is PHP ), but today we will talk about what is JavaScript, why JavaScript is used The Answers to all such questions and much other information about JavaScript, you are going to get here today. Hope this information will work for you.

Who invented JavaScript?

JavaScript language was invented by Brendan Eich in 1995. JavaScript is inspired by Java Programming Language. The first name of JavaScript was Mocha which was named by Marc Andreessen, Marc Andreessen is the founder of Netscape and in the same year Mocha was renamed LiveScript, and later in December 1995, it was renamed JavaScript which is still in trend.

What is JavaScript?

JavaScript is a client-side scripting language used with HTML (Hypertext Markup Language). JavaScript is an Interpreted / Oriented language called JS in programming language JavaScript code can be run on any normal web browser. To run the code of JavaScript, we have to enable JavaScript of Web Browser. But some web browsers already have JavaScript enabled.

Today almost all websites are using it as web technology, mind is that there is maximum scope in JavaScript in the coming time, so if you want to become a programmer, then you can be very beneficial to learn JavaScript.

JavaScript Hello World Program

In JavaScript, ‘document.write‘ is used to represent a string on a browser.

<script type="text/javascript">
	document.write("Hello World!");
</script>

How to comment JavaScript code?

  • For single line comment in JavaScript we have to use // (double slashes)
  • For multiple line comments we have to use / * – – * /
<script type="text/javascript">

//single line comment

/* document.write("Hello"); */

</script>

Advantages and Disadvantages of JavaScript

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Niraj Kafle

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The essential JavaScript concepts that you should understand

As a JavaScript developer of any level, you need to understand its foundational concepts and some of the new ideas that help us developing code. In this article, we are going to review 16 basic concepts. So without further ado, let’s get to it.

#javascript-interview #javascript-development #javascript-fundamental #javascript #javascript-tips

Ajay Kapoor

1626321063

JS Development Company India | JavaScript Development Services

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Santosh J

1622036598

JavaScript compound assignment operators

JavaScript is unarguablly one of the most common things you’ll learn when you start programming for the web. Here’s a small post on JavaScript compound assignment operators and how we use them.

The compound assignment operators consist of a binary operator and the simple assignment operator.

The binary operators, work with two operands. For example a+b where + is the operator and the a, b are operands. Simple assignment operator is used to assign values to a variable(s).

It’s quite common to modify values stored in variables. To make this process a little quicker, we use compound assignment operators.

They are:

  • +=
  • -+
  • *=
  • /=

You can also check my video tutorial compound assignment operators.

Let’s consider an example. Suppose price = 5 and we want to add ten more to it.

var price = 5;
price = price + 10;

We added ten to price. Look at the repetitive price variable. We could easily use a compound += to reduce this. We do this instead.

price += 5;

Awesome. Isn’t it? What’s the value of price now? Practice and comment below. If you don’t know how to practice check these lessons.

Lets bring down the price by 5 again and display it.
We use console.log command to display what is stored in the variable. It is very help for debugging.
Debugging let’s you find errors or bugs in your code. More on this later.

price -= 5;
console.log(price);

Lets multiply price and show it.

price *=5;
console.log(price);

and finally we will divide it.

price /=5;
console.log(price);

If you have any doubts, comment below.

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