Essentials for javascript programming_JS syntax dictionary_basic knowledge

107 javascript syntax dictionary compiled by netizens for the convenience of friends who often use js programming

1.document.write(""); Output statement
2. The comment in JS is //
3. The traditional HTML document sequence is: document->html->(head, body)
4. The DOM order 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 with 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 the file appears When there are multiple forms, you can use document.forms[0], document.forms[1] instead.
19. Window: open the 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="/blog/URL"
25. Take it out 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 elements: 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 Selected to return 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. Radio button Checked is also used to determine whether the group is selected.
34. The value of the drop-down list box: document.forms[0].selectName.options[n].value (n is sometimes used to determine the name of the drop-down list box plus .selectedIndex) Selected value)
35. Definition of string: 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 means it is not found.
38. Take the string A character at the specified position: StringA.charAt(9);
39. Take out the substring of the specified starting point and end point in the string: stringA.substring(2,6);
40. Mathematical function: Math. PI (returns pi), Math.SQRT2 (returns the square root), Math.max(value1, value2) returns the highest 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 date type variables: var today = new Date();
42 .Date function list: 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 the 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) sets 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) sets the 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. Represents the current location: this
47. Used when calling JS functions in hyperlinks :(javascript :) to start with the function name
48. This JS will not be executed in old browsers:
49. Quote a file-style JS:
50. Specify to display in browsers that do not support scripts HTML:
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: