Basic knowledge required to learn js

Some 1.doc ument. write (""); Output statements required for learning js
2. Comments in JS are //
3. The traditional HTML document sequence is: document-> html-> (head, body)
4. the DOM sequence in a browser window is: window-> (navigator, screen, history, location, document)
5. Get the name and value of the element in the form: document. getElementById ("ID of the element in the form"). name (or value)
6. javascript: document. getElementById ("output"). value = document. getElementById ("input"). value. toUpperCase ();
7. value types in JS: String, Number, Boolean, Null, Object, Function
8. Convert the numeric type in JS to the numeric type: parseInt (), parseFloat ()
9. convert numbers in JS to numeric: ("" + variable)
The string length in 10. JS is: (length)
11. The character and character in JS are connected with the + number.
12. The comparison operators in JS include: = equals ,! = Not equal to,>, >=, <. <=
13. Declare variables in. JS using: var for declaration
14. JS judgment statement structure: if (condition) {} else {}
15. loop Structure in JS: for ([initial expression]; [condition]; [upadte expression]) {inside loop}
16. The command for loop abort is break.
17. function Definition in JS: function functionName ([parameter],...) {statement [s]}
18. When multiple form forms appear in the file, you can use document. forms [0], document. forms [1] instead.
19. window: open window. open (), close a window: window. close (), the window itself: self
20. Set the status bar: window. status = "character ";
21. window. alert ("character ");
22. Pop-up confirmation box: window. confirm ();
23. window. prompt ();
24. Specify the position of the currently displayed link: window. location. href = "URL"
25. Retrieve the number of all forms in the form: document. forms. length
26. close the output stream of the document: document. close ();
27. String append connector: + =
28. Create a document element: document. createElement (), document. createTextNode ()
29. method for getting the element: document. getElementById ()
30. Set the value of all text members in the form to NULL:
Var form = terraform Doc ument. forms [0]
For (var I = 0; I If (form. elements. type = "text "){
Form. elements. value = "";
}
}
31. Check whether the check button is selected in JS: document. forms [0]. checkThis. checked (the checked attribute indicates whether to select and return TRUE or FALSE)
32. Single-choice button group (the names of Single-choice buttons must be the same): Take the length of Single-choice button Group document. forms [0]. groupName. length
33. The single-choice button group also uses checked to determine whether it is selected.
34. value of the drop-down list box: document. forms [0]. selectName. options [n]. value (n sometimes adds. selectedIndex to the name of the drop-down list box to determine the selected value)
35. String definition: var myString = new String ("This is lightsword ");
36. Convert string to uppercase: string. toUpperCase (); Convert string to lowercase: string. toLowerCase ();
37. Return the position where string 2 appears in string 1: String1.indexOf ("String2 ")! =-1 indicates no.
38. Take a character at the specified position in the string: StringA. charAt (9 );
39. Retrieve the substring of the specified start point and end point in the string: stringA. substring );
40. mathematical functions: Math. PI (returns the circumference rate), Math. SQRT2 (return to the initiator), Math. max (value1, value2) returns the most value of the two numbers, Math. pow (value1, 10) returns the tenth power of value1, Math. round (value1) Rounding function, Math. floor (Math. random () * (n + 1) returns a random number.
41. Define a Date variable: var today = new Date ();
42. date function list: dateObj. getTime () Get the time, dateObj. getYear () returns the year, dateObj. getFullYear () is the four-digit year, dateObj. getMonth () returns the month, dateObj. get date (), dateObj. getDay () returns the date (dateObj. getHours () returns the hour, dateObj. getMinutes (), dateObj. getSeconds () returns the second, dateObj. setTime (value) sets the time, dateObj. setYear (val): Year, dateObj. setMonth (val) sets month, dateObj. setDate (val) sets the date, dateObj. setDay (val) specifies the day of the week, dateObj. setHours: Set the hour, dateObj. setMinutes (val) set the score, dateObj. setSeconds (val) is set to second [Note: this date and time start from 0]
43. FRAME representation: [window.] frames [n]. ObjFuncVarName, frames ["frameName"]. ObjFuncVarName, frameName. ObjFuncVarName
44. parent indicates the parent object, and top indicates the top object.
45. Open the parent window of the Child Window: opener
46. indicates the current location: this
47. when calling the JS function in the hyperlink, use: (javascript :) to start with and add the function name
48. Do not execute this JS in the old browser:
49. Reference a file-Type JS: