JavaScript basic Data type

String Object

Creating objects
var S1 = new String ("Haha xiaofan")
var s2 = "HAha2"
String object property length, traversing string
document.write (S1.length)
for (var i in S1) {
document.write (i);
document.write (S1[i]);
}
Uppercase and lowercase conversions
document.write (S2.touppercase ());
document.write (S2.tolowercase ());
Gets the specified character
document.write (S1.charat ("3"));
document.write (S1.charat (3));
Query string
S1= "FFFXXXHHH1HFFH1";
document.write (S1.search ("F")); Returns the subscript of the character that matches to the first one
document.write (S1.match ("H1") [0]); The return is an array, here takes the first one
Replace replacement
document.write (S1.replace ("F", "fxh")); The original string does not change
Split split
document.write (S1.split ("X"));
Concat connection
document.write (S1.concat ("Fanxuanhui"));
SUBSTR Intercept string
document.write (S1.SUBSTR); Fetch 2 from the 1th index position
Substring
document.write (s1.substring (1,3)); Starting at index 1 fetch to index 3


Array arrays

Create an array
var arr = [n/a];
var arr1 = new Array (1,2,3,4, "a"); //
var arr2 = new Array (3); Declares an array that can put 4 objects
Length method
document.write (arr.length);
document.write (arr1.length);
The Join method. The join in JS is the method of the array. A join in Python is a method of string that connects the values in the list
var ret = ["haha", "fxh"].join ("----"); haha----fxh
Reverse reversal
var arr = [1,5,32,10];
document.write (Arr.reverse ());
Sort sorts. As a string after the comparison of the sort is asii code.
document.write (Arr.sort ());
Sort by number
function Mysort (A, b) {
if (a > B) {
return 1;
}else if (a < b) {
return-1;
}else{
return 0;
}
}
function Mysort (A, b) {return a-A;}
document.write (Arr.sort (Mysort));
Two-dimensional array: array of nested arrays
var arr2 = [[1,2,3],[3,4,5]];


Date Object

Create a Date Object
var date_obj = new Date (); Current time
document.write (Date_obj.tolocalestring ());
var date_obj1 = new Date ("2017/11/30 11:20");
var date_obj1 = new Date (5000); Unix System Birth Time +5000ms
Doucment.watch (Date_obj.toutcstring ()); World Standard Time

Date_obj.getfullyear (); Years
Date_obj.getmonth (); Month 0-11
Date_obj.getdate (); Day
Date_obj.getday (); Day of the week 0-6
Date_obj.getminutes ();

JavaScript basic Data type