PHP Learning Day06 notes (first knowledge JS)

· JS full-name JavaScript, is a Web page in the use of scripting language, JS is very powerful, you can implement various functions and special effects of HTML pages.

· JS Annotation method: Similar to other languages, JS in the annotation method is

• Single-line comment//xxxxx ...

• Multi-line Comment/*xxxxxxxx

xxxxxxxx*/

· The output syntax of JS:

alert ("Information that needs to be output, which can be a function or an expression"); Pop-up box display information content

confirm ("need to output de information"); The popup dialog (user interaction type) can be submitted via the Confirm and cancel button.

prompt ("user input information"); POPs up a dialog box that allows the user to enter

• Embed JS location: generally written at the bottom of the page content or the bottom of the body, because the page loading content order is from top to bottom.

Embedded format is <script type= "Text/javascript" > Content </script>

· JS basic knowledge of the program

• All characters are in English state, such as common semicolons, commas, and parentheses.

• In most cases, the end of each statement should be preceded by a semicolon;

• Line breaks after each piece of code ends

• The symbols for each program statement should be echoed back and forth.

· JS data type

• The stored name of the data in the program is called a variable, and the method of declaring the variable is the var variable name

Because JS is a weakly typed language, variable data types are not differentiated when declaring variables, but are automatically converted when stored

JS data types include int (integer type), float (single-precision decimal type), double (double-precision decimal)

Decimal (decimal), Money (currency type), char (character type) string (String type)

Boolean (Boolean: Return value only True and False) DateTime (date type)

• Forced conversion of data types =parse variable type (variable) of forced conversion; For example, Var x=parseint (x) is the conversion of X to integer type;

• Operator Expression: +-*/for subtraction,% for remainder (e.g. 5&2=1)

• Logical operators: && (and): Both are true and the result is true;

|| (OR): As long as one of them is true, the result is true;

！ (non): reverse the result.

• comparison operator: = = (equals);! = (not equal to);> (greater than);< (less than); >= (greater than or equal to);

<= (less than or equal)

+ You can stitch strings;

A ==b? X:y (indicates selection judgment, output x If the result is true, output y if the result is false)

　　　　

PHP Learning Day06 notes (first knowledge JS)