Detailed explanation of Array() array function in javascript_javascript skills

The importance of arrays in programming languages ​​is self-evident. Arrays in JavaScript are also one of the most commonly used objects. Arrays are ordered collections of values. Due to weak types, arrays in JavaScript are very flexible and powerful. Unlike arrays in strongly typed high-level languages ​​such as Java, which can only store elements of the same type or its subtypes, JavaScript can store multiple types of elements in the same array, and the length can also be dynamically adjusted, as the data increases or Reduce automatic changes to array length.

Array() is a built-in constructor function used to construct arrays. Arrays are mainly created in the following three ways:

array = new Array()
array = new Array([size])
array = new Array(element0, element1, ..., elementN)

Parameters

The parameter size is the expected number of array elements. In the returned array, the length field will be set to the value of size.

The parameters element ..., elementn are parameter lists. When the constructor Array() is called with these arguments, the elements of the newly created array are initialized to these values. Its length field will also be set to the number of parameters.

Return value

Returns the newly created and initialized array.

If the constructor Array() is called without parameters, the returned array will be empty and the length field will be 0.

When calling the constructor, passing it only a numeric parameter, the constructor will return an array with the specified number of elements as undefined.

When Array() is called with other parameters, the constructor will initialize the array with the values ​​specified by the parameters.

When a constructor is called as a function without using the new operator, it behaves exactly like when it is called with the new operator.

Array object method

Array object properties

concat() method:

Merge arrays

[1,2]concat([3,4],[5,6]);//[1,2,3,4,5,6]

join() method:

<script type="text/javascript">
 var a = [1,2,3];
 a.join("");// =>"123"
</script>

pop() method:

Remove the last element of the array and return it

<script type="text/javascript">
 var fruits = ['apple','banana','pineapple'];
 fruits.pop();// pineapple 
 console.log(fruits);//["apple","banana"]
</script>

shift() method:

Deletes and returns the first element of the array.

<script type="text/javascript">
 var a = [1,2,3];
 a.shift();//1
 console.log(a);//[2,3]
</script>

slice(start,end)

Method: intercept a certain part of the array without any modification to the original array.

<script type="text/javascript">
  var num = ['a','b','c','d','e'];
  console.log(num.slice(1,4));//["b","c","d"]
  console.log(num);//["a","b","c","d","e"]
</script>

splice(start,delete_count,i1,i2…)

Method: Delete array elements and add new elements at the same time. i1 and i2 are the new elements to be inserted

<script type="text/javascript">
 var arr = ['js','css','html','php','c'];
 arr.splice(1, 2,'python','jquery');//["css","html"]
 console.log(arr);//["js","python","jquery""php","c"]
</script>

The above content is to introduce you to the detailed explanation of the Array() array function in JavaScript. I hope it will be helpful to you.