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How to convert a number to an array in JavaScript?

王林
王林forward
2023-08-29 13:25:091303browse

如何在 JavaScript 中将数字转换为数组？

In JavaScript, there are many built-in methods to convert numbers to arrays. The simplest one is the split() method. We can also use map(), reduce() or form() methods to perform tasks. This article discusses some of the most popular methods of converting numbers to arrays and provides examples of when and how to apply each technique.

Now the question is, why do we need to convert numbers to arrays? Well the reason could be to split a phone number into separate numbers or a date into its component parts (parsing a date), or it could be useful when performing mathematical operations on separate numbers.

Method 1: Through the split() method

Now, let’s take a look at the split() method. It is a useful tool for breaking strings into smaller substrings and converting them into numbers. It can then even convert the number into an array by converting it to a string and splitting it into individual numbers. Let's see it by implementing the split() function as shown in the example.

Example

In this example, we use the function toString() to convert an integer to a string. Then use the split() function to split the string into an array of individual characters. The final output will be an array of strings, each string representing a digit of the original number. 

<html>
<body>
   <p id="print"></p>
   <script>
      let number = 12345;
      let numberArray = number.toString().split("");
      document.getElementById("print").innerHTML = numberArray;
   </script>
</body>
</html>

Method 2: Use map() method

By using the map() method, you can create a new array containing the output of executing a given function on each element in the calling array. It can also be used to convert numbers to arrays by creating an array of numbers using the map() method. Below is the instruction on how to convert an integer to an array using the map() method -

Example

In this example, we first use the function toString() { [native code] }() method Convert an integer to a string. This string is then converted to an array using the Array.from() function. Finally, we use the map() method to convert the string array into an integer array

<html>
<body>
   <p id="print"></p>
   <script>
      let number = 12345;
      let numberArray = Array.from(number.toString(), Number).map(Number);
      document.getElementById("print").innerHTML =numberArray;
   </script>
</body>
</html>

Method 3: Using For Loop

This method is the simplest one, it uses a for loop to iterate the numbers and convert them into an array of numbers.

Example

In this example, we first convert a number to a string using the toString() method. We then use a for loop to iterate over the numbers and use the parseInt method to convert the individual numbers and push them into an array. 

<html>
<body>
   <p id="print"></p>
   <script>
      let number = 12345;
      let numberArray = [];
      for (let i = 0; i < number.toString().length; i++) {
         numberArray.push(parseInt(number.toString()[i]));
      }
      document.getElementById("print").innerHTML = numberArray;
   </script>
</body>
</html>

Method 4: Use the reduce() method

The reduce() method is an array method that can be used to reduce an array to a single value. In this example, we will use the reduce() method to convert a number into an array of numbers

Example

In this example, we first use the `toString()` method. We then use the split() method to split the string into an array of individual characters. Finally, we iterate over the character array using the "reduce()" method, parsing each character into an integer and adding it to the final array, which is the accumulator in this case. 

<html>
<body>
   <p id="print"></p>
   <script>
      let number = 12345;
      let numberArray = number.toString().split('').reduce((acc, curr) => {
         return [...acc, parseInt(curr)];
      }, []);
      document.getElementById("print").innerHTML=numberArray ;
   </script>
</body>
</html>

Method 5: Use Array.from() method

Now, we will learn another way to convert or change a number into an array. So, here we will use Array.from method(). Array.from generates a new array from an iterable or array-like object. In this case, we can use the Array.from() method to convert the string representation of a number into an array of single numbers.

Example

Now, let us look at the code of the above method. 

<html>
<body>
   <p>Original number: 12345</p>
   <p id="result"></p> 
   <script>
      const num = 12345;
      const arr = Array.from(num.toString(), Number);
      document.getElementById("result").innerHTML = arr.join(", ");
   </script>
</body>
</html>

in conclusion

In JavaScript, there are multiple ways to convert a number to an array, and each method has advantages and disadvantages. The Split()' method is the simplest, while the map()', 'for' and reduce()' methods are more powerful and adaptable, but require more expertise. You can choose the method that best meets your needs based on the specific requirements of your project.

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