VUE-es6,
Es6:
Es: EMCAScript 6 (es2015)
Emca: International Standards Organization
I. constants and variables
Const a = 'hello' constant const can be defined only once and cannot be repeated
The value of the variable declared by const cannot be changed, which means that once the variable is declared by const, it must be initialized immediately and cannot be left for future value assignment.
The let Command is a new command added in es6. it is used to declare variables. Its usage is similar to var. It declares variables and is only used within the code block where the let Command is located.
Let: defines a block-level scope variable.
Let it be defined in use first (no variable is promoted)
1. Differences between let and var
A,Let it be defined in use first (no variable is promoted)
B. let cannot be defined repeatedly, but can be modified.
C. var can be defined multiple times
The scope of const is the same as that of the let Command. It is only valid within the block-level scope of the declaration.
For example:
<! DOCTYPE html> View Code
Supplement:
Js data type:
String, array, number, null, undefined, boolean, object
Basic Data Type:
String, number, null, undefinedboolean
Reference Type:
Array, object
Ii. template string
A. Use it using reverse quotation marks. variables can be used in strings.
B. It can be processed as a normal string.
C. Multi-line strings can be used.
For example:
<! DOCTYPE html> View Code
III,SolutionConstruction variable
A. Array Structure assignment: Values of data elements are assigned to variables in sequence.
<!DOCTYPE html>View CodeIv. object extension
Deconstruct can be used not only for arrays, but also for objects.
A. attributes in objects can be abbreviated
B. The methods in the object can also be abbreviated
<! DOCTYPE html> View Code5. Function Extension
A. Default function parameters can be provided.
B. The remaining parameters can be replaced by the three vertices)
For example:
Function fun (a,... B) {} fun (, 33) then: B = []<!DOCTYPE html>View CodeVi. Array Extension
A. traverse the Array
(1) Use forEach Loop
If we add 1 to the original base, we will use map to traverse the array. We will use return (map () to put the function in brackets when we regret it)
For example:
arr.forEach(function (value,index) { console.log(value); }) var arr2 = arr.map(function (value,index) { return value+1 })B. determine whether an array exists.
(1) Use indexOf
(2) include the use of DES
console.log(arr.indexOf(1000)) console.log(arr.includes(201))C. filter the Array
var arr4 = arr.filter(function (value,index) { return value > 50 }) console.log(arr4);<!DOCTYPE html>View Code<! DOCTYPE html> Maintain Student Information
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