Summary of Array object method attributes in javacsript

There are three main properties: constructor; length; prototype;

Constructor (English meaning: constructor): Returns a reference to the array function that created this object. For example: var arr=new Array(); arr.constructor=Array;

length (English meaning: length): Set or return the number of elements in the array. Note: The length is always 1 greater than the last subscript of the array; set the length of the array: if the array is longer than the set length, the array will be truncated. If the array length is shorter than the set length, undefined will be added later;

Prototype (English meaning: prototype): enables you to add properties and methods to objects (prototype chain, inheritance of properties);

There are 12 commonly used methods:

　concat(arrayX); used to join two or more arrays; (arrayX is required, the array to be linked) (the original array is not changed, but another new array is created);

join( [separator]); is used to put all elements in the array into a string. (Separator English meaning: separator);

pop(); delete and return the last element of the array; (If the array is already empty, pop() does not change the array and returns an undefined value.); (First in, last out);

push();Adds one or more elements to the end of the array and returns the new length. (First in, last out);

Reverse(); Used to reverse the order of elements in an array; (Change the original array without creating a new array.);

shift() ;Remove the first element from the array and return the value of the first element. (Change the original array without creating a new array.);

　slice(start,[end]);Returns the selected elements from the existing array. (start is a negative number, then it specifies the position starting from the end of the array. That is, -1 refers to the last element, -2 refers to the second-to-last element, and so on.) ((start,end)== =[start,end] includes the front and not the end);

Sort([function]); Sort the elements of the array. (according to the ascii code table); such as: (arrange according to the size of the numbers: function sortNum(a,b){return a-b});

splice(index,number,[item]);index: Position; number: quantity; item: item to be replaced;

toString(); Convert the array to a string and return the result (same effect as push without parameters);

unshift ();Adds one or more elements to the beginning of the array and returns the new length;

　valueOf();Returns the original value of the Array object.

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