JS Collection Study Notes (Part 1)_Basic Knowledge

1.document.write(""); Output statement
2. The comment in JS is //
3. The traditional order of HTML documents 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 number of the element in the form").name (or value)
6. A lowercase to uppercase JS: document.getElementById("output").value = document.getElementById("input").value.toUpperCase();
7. Value types in JS: String, Number, Boolean, Null, Object, Function
8. Convert character type to numeric type in JS: parseInt(), parseFloat()
9. Convert numbers in JS to character type: ("" variable)
10. The length of string in JS is: (length)
11.Characters in JS are connected to characters using the symbol.
12. The comparison operators in JS are: == equal to, != not equal to, >, >=, <.>13. Use: var to declare variables in JS
14.Judgment statement structure in JS: if(condition){}else{}
15. Loop structure in JS: for([initial expression];[condition];[upadte expression]) {inside loop}
16. The command to terminate the loop is: break
17. Function definition in JS: function functionName([parameter],...){statement[s]}
18. When multiple forms appear in the file, you can use document.forms[0], document.forms[1] instead.
19. Window: open window window.open(), close a window: window.close(), window itself: self
20. Status bar settings: window.status="character";
21. Pop-up prompt message: window.alert("character");
22. Pop up confirmation box: window.confirm();
23. Pop up the input prompt box: window.prompt();
24. Specify the location of the currently displayed link: window.location.href="URL"
25. Get the number of all forms in the form: document.forms.length
26. Close the output stream of the document: document.close();
27. String append concatenation: =
28. Create a document element: document.createElement(), document.createTextNode()
29. Method to get elements: document.getElementById()
30. Set the values ​​of all text members in the form to empty:
var form = window.document.forms[0]
for (var i = 0; i if (form.elements.type == "text"){
form.elements.value = "";
}
}
31. Determine whether the check button is selected in JS: document.forms[0].checkThis.checked (the checked attribute represents whether it is selected and returns TRUE or FALSE)
32. Radio button group (the names of the radio buttons must be the same): take the length of the radio button group document.forms[0].groupName.length
33. The radio button group also uses checked to determine whether it is selected.
34. The value of the drop-down list box: document.forms[0].selectName.options[n].value (n sometimes uses the name of the drop-down list box plus .selectedIndex to determine the selected value)
35. Definition of string: var myString = new String("This is lightsword");
36. Convert a string to uppercase: string.toUpperCase(); Convert a string to lowercase: string.toLowerCase();
37. Return the position where string 2 appears in string 1: String1.indexOf("String2")!=-1 means it was not found.
38. Get a character at the specified position in the string: StringA.charAt(9);
39. Take out the substring with specified starting point and end point in the string: stringA.substring(2,6);
40. Mathematical functions: Math.PI (returns pi), Math.SQRT2 (returns square root), Math.max(value1, value2) returns the greatest value of 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 date variables: var today = new Date();
42. List of date functions: dateObj.getTime() gets the time, dateObj.getYear() gets the year, dateObj.getFullYear() gets the four-digit year, dateObj.getMonth() gets the month, dateObj.getDate() gets Day, dateObj.getDay() gets the date, dateObj.getHours() gets the hours, dateObj.getMinutes() gets the minutes, dateObj.getSeconds() gets the seconds, dateObj.setTime(value) sets the time, dateObj.setYear(val) Set the year, dateObj.setMonth(val) sets the month, dateObj.setDate(val) sets the day, dateObj.setDay(val) sets the day of the week, dateObj.setHours sets the hours, dateObj.setMinutes(val) sets the minutes, dateObj.setSeconds( val) Set seconds [Note: This date and time starts from 0]
43. FRAME representation: [window.]frames[n].ObjFuncVarName,frames["frameName"].ObjFuncVarName,frameName.ObjFuncVarName
44.parent represents the parent object, top represents the top object
45. The parent window that opens the child window is: opener
46. Indicates the current location: this
47. When calling a JS function in a hyperlink, use: (javascript:) to start and then add the function name.
48. This JS is not executed in old browsers:
49. Quote a file-style JS:

51. When there are both hyperlinks and ONCLICK events, the old version of the browser will redirect to a.html, otherwise it will redirect to b.html. Example: dfsadf

52. The built-in objects of JS are: Array, Boolean, Date, Error, EvalError, Function, Math, Number, Object, RangeError, ReferenceError, RegExp, String, SyntaxError, TypeError, URIError
53.Line break in JS:n
54. Window full screen size: <script></script> <script>function fullScreen(){ this.moveTo(0,0);this.outerWidth=screen.availWidth;this.outerHeight=screen.availHeight;}window.maximize=fullScreen;</script>55.all in JS represents all the elements below it