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Where can the Q1:js be placed?
A1:
1. Put in 2. Put in the external file, the file suffix is. js, with <script src= "Xx.js"/> The external file into HTML;
3. Write in HTML <body> tags, through <script type= "Text/javascript" ></script> to mark this is a section of JS code;
Q2:js comment How to write?
A2:js comments are the same as Java annotations, "//" is a single-line comment, "/* */" is a multiline comment;
Q3: What is a variable?
A3: A variable is a container for storing values;
The method of defining variables in JS: var A; Define a variable A, type VAR (note: All variable types in JS are Var)
Assign a value to a variable: a = 1;
You can also define and assign values to variables at the same time: var a = 1;
How to use the branch judgment statement in Q4:js?
A1: Branch Judgment statement:
if (EXP1)
{
Operation when EXP1 is satisfied
}
Else
{
Operation when EXP1 is not satisfied
}
Give me a chestnut:
1 varA = "man";//define a variable A, and assign him the string "man";2 if(A = = "man")//if the value of a is equal to "man", execute the code inside the curly braces below;3 {4Alert ("Boy! ");//the pop-up window shows "Boy!";5 }6 Else if(A = = "Woman")//if the value of a is equal to "woman", execute the code inside the curly braces below;7 {8Alert ("Girl! ");//the pop-up window shows "Girl!";9 }Ten Else //all previous if are not compliant One { AAlert ("Shemale! ");//pop-up window shows "Shemale!" "; -}
Q5: What is a function?
A5: A function is a block of code that accomplishes a particular function;
Explanation: We put the code that completes a particular function into a block of code, give it a name, and use it to invoke it directly by name;
To define a function:
Function name ()
{
function code;
}
Give me a chestnut:
1 function add () 2 { 3 // This function is to add two numbers, and the popup window displays 4 var a = 1; 5 var b = 2;< /span>6 var sum = a + b; 7 alert (sum); 8 }
What are the common built-in methods in Q6:js?
A6:
1.document.write ("text displayed on the page"); Write content directly to the HTML output, which is displayed directly on the page
2.alert ("Pop-up window display text"); Warning dialog box (Message dialog box)
3.conform (); Confirmation dialog box (with return values and parameters, see examples)
4.prompt (); Question dialog box (with return values and parameters, see examples)
5.window.open (); Open a new window (multiple optional parameters)
6.window.close (); Close the current window (if you want to close the specified window, first get the specified Window object, obj, and then use this method to close, Obj.close ();)
Give me a chestnut:
1<script type= "Text/javascript" >2 varresult = Confirm ("Are you a boy?") ");//Click the Confirm button to return true,3 if(Result = =true)4 {5Alert ("You're a Boy");6 }7 Else8 {9Alert ("You're a Girl");Ten } One</script>
1 <script type= "JavaScript" >2 function tiwen ()3 { 4 var obj = prompt ("What's your name?") "," Xiao Hua "); // obj is the value entered in the input box, which defaults to the second parameter value: "Xiao Hua" 5 alert (obj); // warning Bullet box showing results 6 }7 </script> 1 <script type= "javascript" >2 function Openwindow () { 3 var obj = window.open (" http://www.baidu.com "," _blank "," width=600px,height=300px,top=500px,left= 500px " 4 } 5 </script> 1 <script type= "javascript" >2 function Clozen () { 3 var obj = var obj = window.open (" http://www.baidu.com "," _blank "," width=600px,height=300px,top=500px,left=500px " 4 obj.close (); // 5 6 window.close (); // Close the current window 7 } 8 </script> Q7: Common ways to get DOM nodes:
A7:
1. var a = document.getElementById ("Value of ID");//Get the node by its ID property
2. var B = Document.getelementsbyname ("Value of name"); Gets the node
3. var c = document.getelelentsbytagname ("tag name") via the label's Name property;//Get node by tag name
hold a chestnut:
1 function GetNode () { 2 var a = document.getElementById (" Add " 3 var b = Document.getelementsbyname (" Confirm " 4 var C = Document.getelementsbytagnam E ("Input" 5 alert (a); 6 alert (b); 7 alert (c); 8 }
Q8: How do I manipulate DOM nodes to change the content and style of HTML?
A8:
1. Gets and changes the text within the tag through the innerHTML property of the node:
for chestnuts:
1 function changedom () 2 {3 var divdom = document.getElementById ("Title1"); 4 var text = divdom.innerhtml; 5 alert (text); 6 divdom.innerhtml = "becomes title two"; 7 alert (divdom.innerhtml); 8 }
2. Change the style by using the node's style property:
Give me a chestnut:
1<p id= "Pcon" >hello world!</p>2<script>3 varMyChar = document.getElementById ("Pcon");4Mychar.style.color= "Red";//color set to red5Mychar.style.fontsize= "20";//font size set to;6Mychar.style.backgroundColor = "Blue";//background color set to blue7Mychar.style.display= "None";//Hide Tag Blocks8mychar.style.display= "Block";//Show Tag Block9</script>
3. Increase the style of the node by assigning a value to the class of the node:
Give me a chestnut:
1<style type= "Text/css" >2 . style1{3 color:red;4Font-size:20;5 Backgroundcolor:blue;6 }7</style>8<p id= "Pcon" >hello world!</p>9<script>Ten varMyChar = document.getElementById ("Pcon"); OneMychar.classname = "Style1"; A</script>
JavaScript Introductory QA Summary
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