About Javascipt Basics 2

To undertake the essay of the previous essay

The following is about logical thinking about the same as the programming language

Iv. operators

1. Arithmetic Operators (+-*/%) add, subtract, multiply, divide, and balance, where% is the remainder operation

example: var total = (1 + 4) * 5;

var i = 100;

var temp = (i–20)/2;

Alert ("ten" +)//return 1020;

Alert (+)//return 30;

2. Post increment/decrement operator + +,--

example: var i = 10;

var a = i++; (equivalent to i = i + 1)

Alert (a); (value is 10?) Why is it? because it is preceded by a post increment, a before I increases by 1 the value of I is obtained)

var i = 10;

var a = ++i;

Alert (a); (so The value is 11)

3. comparison operator (<, >=, <=, = =,!=,===,!==)

Example: Alert (> 5); Outputs True

var i = 100;

var n = 100;

Alert (i = = n); Outputs true;

Alert (i! = n); Outputs false;

Alert (i = = n)//outputs true; (all equals required numeric and type Equality)

4. Logical Operators (&&, | |,!)

&&: logic and (true after Current)

|| : Logical OR (current after which one is true will be True)

！ : Logical non (true to False is false to True)

example: var i = 8;

Alert (i<5 && i<10); Outputs false (8 is not less than 5 so the former is false because it is && so it is False)

Alert (i > | | i < 10); Outputs true (8 is not greater than 100 so the former is false then 8 is less than 10 so the latter is true because it is | | So That's True)

Alert (! ( > 5)); Outputs false (10 greater than 5 is true and then because it is!) Not true so it is False)

The precedence of an operator is previously incremented, then *,/,%, then +,-, then compared (<,>,<=,>=,!=), and finally logic (&&,| |,! ）

V. JavaScript annotations

Single-line Comment

/* ... * * Multi-line comment

Note: multi-line annotations cannot be nested with each other

Vi. Program Flow control (branch Statements)

first, Conditional Statement If syntax:

If (condition) statements1 else statement2

example: if (> 5) {alert ("hello world");}

var i = 90;

If (i >) {alert (i + "greater than 100");} (first use if to determine if I is greater than 100 if the statement is executed in curly braces if it is not transferred to else Execution)

else if (i >) {alert (i + "greater than 80");} (this else also has if to determine the remaining process is the same as Above)

Else{alert (i + "less than 100");}

second, Switch Statement syntax:

Switch (expression) {case value://statement, case value://statement break; default://statement}

example: var i = 25;

Switch (i) {(switch to determine the expression in Parentheses)

Case 25:alert (i + "equals 25"); (executes The statement if the result of the expression corresponds to a Type)

Break (prevent continued Execution)

Case 100:alert (100);

Break

Default:alert (' Other '); (executes The statement if it does not correspond to the value of the Case)

}

The next statement about the loop

About Javascipt Basics 2