JS creates a new map object and operates on it

For map, many of the partners in the array may often confuse and use a vague concept, and I'll summarize my own experience here:

Array:

Generally we create this:

var arr = new Array ();

or direct: var arr = [];

Then operate on the array:

1, add elements:

var obj = ' The element you want to add ';

Arr.push (obj);

2, find the element:

var obj = ' You need to find the element ';

Arr.indexof (obj); The return value is-1, which means that obj does not exist in this array, and if not, returns the position of the element in the array, starting with 0.

3, delete the element:

Arr.pop ()//delete and return the last element

For example: var arr = [n/a]; var B = Arr.pop (); As a result, b = 3,arr = [+];

Arr.shift ()//delete and return the first element

Arr.splice (index,1)//delete the next 1 elements starting from the index position

var arr = [1,2,3,4,5];

For example: Arr.splice (2,2)//return [3,4],arr = [1,2,5]

Map creation:

var map = {};

To add an element:

For example, add: name = 1;

map[' name ']=1;

JS creates a new map object and operates on it