Front-end basic-javascript sixth day

Button not available

Button can not be used disabled not be able to use the meaning

btn.disabled = "Disabled" | | Btn.disabled = true;

Grey

Attention:

1. Because the button is a double label, you want to change his value, using InnerHTML, not value.
2. Turn off timer clearinterval (timer name); The timer is no longer

SetTimeout of the timer ()

SetInterval (fn,5000); each interval 5 seconds, go to execute function fn One time

SetTimeout (fn,5000); after 5 seconds, go to the FN function and execute only once

A deeper view of the timer difference

SetInterval is queued for execution.

1 seconds, and the time of the executed program is 2 seconds     The last code that was not executed is queued is executed immediately. This is the actual execution interval of 2 seconds

The SetTimeout delay time is 1 seconds , and the code to execute takes 2 seconds to execute , The last time the code is executed is 3 seconds .

operator

Unary operator + +, ---+-+5-6

logical Operators ! && | |

basic operator +,-, *,/,%

relational operator , <, >=, <=, = = =, =,! =,!==

= value = = = = = = = =

conditional operator (ternary operator) ? :

assignment operator + =,-=, *=,/=,%=

A+=5 A= A + 5

comma operator , var a=0,b=0;

String Object Common method conversion to string

1. + "" "" "" "=" 2 "" "AB" = "2ab"

2. String () conversion to Strings

3. ToString(base) ; Cardinality is the binary

var txt = 10;

Txt.tostring (2) binary 1010

get character position method

CharAt, gets the corresponding position character (argument: character position)

charCodeAt get the corresponding position character Unicode encoding (parameter: Character position)

2. button not available disabled = "Disabled" | | True
4. SetTimeout only executes once setinterval executes many times
6. Recursive invocation : The function calls itself function recursive call does not advocate the function name But like to use the Arguments.callee return is executing functions itself
8. logical Operators   with && or | |          No! ! > && > | |
10. 2&&0 0 1&&8 0&&3 0 1| | 0
12. converted to Character Type
    var num = 12345;
    num+ ""
    String (num);
    Num.tostring (); Ten- Step system
    Num.tostring (2) binary
14. returns characters based on character position
    CharAt ( index number )

var txt = "ABCDE";

Txt.charat (3); D

charCodeAt (3) Unicode encoding

Front-end basic-javascript sixth day