Detailed explanation of how to create an array in JavaScript

Creating Arrays in JavaScript
Using Arrays
Convert array to split string
Adding elements to an array
Filtering an Array
Delete the specified element from an array
Summarize

Creating Arrays in JavaScript

1. Create an array using new

var arr = new Array(); //Creates an empty array

2. Create arrays using array literals (more commonly used)

Literal: A method of expressing a fixed value

You can tell what data type it is at a glance, for example, 8 is a numeric type at a glance

//1. Create an array using array literals (square brackets) var arr = []; //Create an empty array var arr1 = [1,2,'student',true]; //The array can contain any type of data and must be separated by commas

3. What is an array element?

An array can store a group of data in a single variable. An array element is an element stored in an array, and there is no restriction on its type.

Using Arrays

1. Get array elements - use the index, which is the subscript. The subscript starts from 0 and is very similar to C language.

console.log(arr[2]);

2. Traverse the array

var arr = ['red','green','blue'];
for(var i = 0;i < 3;i++){
    console.log(arr[i]);
}
//Print array length console.log(arr.length);
//Dynamically detect array length for(var i = 0;i < arr.length;i++){
    console.log(arr[i]);
    }

What is traversal?

Access the array elements from the beginning to the end once. The i inside is a counter used as an index number. arr[i] accesses the array elements. The index number has nothing to do with the array length.

//Classic case print array maximum value var arr = [2,6,1,77,52,25,7,99];
var max = arr[0];
for(var i = 0;i < arr.length;i++){
    if(max < arr[i]){
        max = arr[i];
        }
    }
    conaole.log('The maximum value in the array is ' + max);

Convert array to split string

var arr = ['red','green','blue','pink'];
var str = '';
for(var i = 0;i < arr.length;i++){
	str+=arr[i]+'|'; //You can also use var sep = '!'; str+=arr[i]+sep;
}
console.log(str);

Adding elements to an array

var arr = ['red','green','blue','pink'];
var str = '';
for(var i = 0;i < arr.length;i++){
	str+=arr[i]+'|'; //You can also use var sep = '!'; str+=arr[i]+sep;
}
console.log(str);

If the index number exists, the array element is replaced. Do not assign a value to the array name directly, otherwise the previous data will be overwritten. For example, arr1 =''; onsole.log(arr1)

Filtering an Array

var arr = [1,2,3,4,5,6,7,8,9,10];
var newArr = [];
console.log(newArr);
for(var i = 0;i < arr.length;i++){
	if(arr[i]>=5)
	{
		newArr[newArr.length] = arr[i];
	}
}

Delete the specified element from an array

//Delete 7 var arr = [1,2,3,4,5,6,7,8,9,10];
var newArr = [];
console.log(newArr);
for(var i = 0;i < arr.length;i++){
	if(arr[i] != 7)
	{
		newArr[newArr.length] = arr[i];
	}
}
console.log(newArr);