JavaScript face questions

1. What is the value of Y and Z?
<script type= "Text/javascript" >
var x = 1;
var y = 0;
var z = 0;
function Add (n) {n=n+1;}
y = Add (x);
function Add (n) {n=n+3;}
z = Add (x);
</script>
are undefined because there is no return value.

2.javascript is object-oriented, how to embody the inheritance relationship of JavaScript?
Use prototype to implement.

3.javascript How to select a checkbox, how to set it invalid?
Document.all.cb1[0].disabled = true;

The input in 4.form can be set to ReadOnly and disable, what is the difference between 2 people?
ReadOnly cannot be edited, but can be selected and copied; values can be passed to the background
Disabled cannot be edited, cannot be copied, cannot be selected, value cannot be passed to the background

What are the commands of the 3 pop-up message reminders in 5.js (Warning window, confirmation window, Information Entry window)?
Alert
Confirm
Prompt

What are the types of input in 6.form?

Text: TextBox
Password: Password box
Radio: Radio button
CheckBox: check box
File: Select a domain
Hidden: Hidden Fields
Button: Buttons
Reset: Reset button
Submit: Form Submit button
Image : Picture button, similar to submit can add a picture to a button ...

What is the difference in the range of 2 variants of 7.javaScript?

Global variables: Active in the current page

Local variables: Valid in method

8. Enumerate the 3 main data types of JavaScript, 2 composite data types and 2 special data types.

Primary data type: String, Boolean, number

Composite data type: function, Object

Special type: null undefined

9. How do I catch an exception in my program?

Window.error

Try{}catch () {}finally{}

10. Write the return result of the function Datedemo, the system time is assumed to be today

function Datedemo () {

var d, s= "Today's date is:";

D = new Date ();

s + = D.getmonth () + "/";

s + = D.getdate () + "/";

s + = D.getyear ();

return s;

}

Result: Today's date is: 7/17/2010

11. Write the results of the program run?

For (i=0, j=0; i<10, j<6; i++, J + +) {

K = i + j;

}

Result: Ten( beware of traps )

12. What are the results of the operation?

function Hi () {
var A;
alert (a);
}

Results: undefined

13. What are the results of the operation?

function Hi () {
var a = null;
alert (a);
}

Result:null

14. What is the browser object model?

Window

Top-level objects

Window.alert (msg)

Window.prompt ()

Window.confirm ()

if (Window.confirm ()) {

...

}

window.open ()

Window.close ()

Document

document.write ()

History

When a user browses a Web page, the browser saves a list of URLs for the most recently visited Web page. This list is represented by the history object.

History.back (): Back

History.forward (): Forward

History.go (n): Positive indicates forward, negative indicates backward

Location

Represents the URL information for the currently open window or frame.

Location.href: redirect

Equivalent to Location.assign (URL)

Location.host: Similar to www.163.com:80

Navigator

Indicates the browser information and JS running environment

Navigator.cookieenabled: This property indicates whether cookies are enabled

Screen

The size and color of the display used to display the Web page

Screen.width/screen.height: Indicates the resolution of the monitor (total width, height)

What is a 15.XMLHTTPRequest object?
Ajax Principles

16. What is the difference between the _blank, _parent, _self, _top, and frame names for the hyperlink's properties of the target?

What are the common objects of 17.javascript?

String, Math, date, and array objects

The difference between 18.innerhtml,innertext,outerhtml,innertext?

Transferred from: http://www.cnblogs.com/joetao/articles/1967017.html

JavaScript face questions