Here are the collection of best Javascripts which are usefull as well as can be used to play prank on other, Thus can be used for fun purpose.

Javascript 1:
javascript:R=0; x1=.1; y1=.05; x2=.25; y2=.24; x3=1.6; y3=.24; x4=300; y4=200; x5=300; y5=200; DI=document.images; DIL=DI.length; function A(){for(i=0; i<DIL; i++){DIS=DI[ i ].style; DIS.position='absolute'; DIS.left=Math.sin(R*x1+i*x2+x3)*x4+x5; DIS.top=Math.cos(R*y1+i*y2+y3)*y4+y5}R++}setInterval('A()',5); void(0);
Open google images. Search for any image. When the result will come, enable the upper javascript and see. Train of images!
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Javascript no: 2
javascript:i=0;c=["red","green","blue","yellow","magenta","orange","pink","violet"]; a=document.links;setInterval('i++;a[i % document.links.length].style.color=c[i % c.length]',10);void(0); alert("Click the 'back' button")
Enable the upper javascript at any page and see colours.
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Javascript no: 3
javascript:a=document.body;b="a.innerHTML";void(eval("2='<center><textarea cols=100 rows=30 id=\"cache\" uzzonchange=\" 2=cache.value\">'+ 2+'</textarea><br></center>'+ 2".replace(/2/gi,b)))
Try this out and view the source of page.
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Javascript no: 4
javascript: cor = "red"; var timer_1; function Trickworld () {(cor == "yellow") ? cor = "red": cor = "yellow"; document.links[10].parentNode.parentNode.style.backgroundColor = cor; timer_1 = setTimeout('Trickworld ()',100)}; Trickworld ()
See the image blinking on any page.
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Javascript no: 5
javascript: x=0; c=["red","yellow"]; setInterval('x=x^1;document.links[2].style.color=c[x]',100);void(0)
Something on page changes its colour.
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Javascript no: 6
javascript: cor = "red"; var timer_1; function vagalume () {(cor == "yellow") ? cor = "red": cor = "yellow"; document.links[20].parentNode.parentNode.style.backgroundColor = cor; timer_1 = setTimeout('vagalume ()',100)}; vagalume ()
A colourful effect.
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Javascript no: 7
javascript:document.body.innerHTML=document.body.innerHTML.replace(/small/g,"medium");void(0)
Some items on page grows.
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javascript no: 8
javascript: i=0; c=["#00ffff","#ff00ff","#ffff00"]; a=document.links;setInterval('i++;b=a[i % 10];b.style.color=c[i % 3]',10);void(0)
Make the index colourful.
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Javascript no: 9
javascript:a=0;x=0;y=0;setInterval("a+=.01;x=Math.cos(a*3)*2;y=Math.sin(a*2)*2;moveBy(x,y)",2);void(0)
This one is earthquake. screen moves dangerly. Suddenly press 'refresh' button.
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javascript no: 10
javascript:b=[]; a=document.images; for(wt=0; wt<a.length; wt++){a[wt].style.position='relative'; b[b.length]=a[wt]}; j=0; setInterval('j++; for(wt=0; wt<b.length; wt++){b[wt].style.left=Math.sin((6.28/a.length)*wt+j/10)*10}; void(0)',1); void(0)
all the pictures do dance. Good with google images.
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javascript no: 11
javascript:R=0; x1=.1; y1=.05; x2=.25; y2=.24; x3=1.6; y3=.24; x4=300;y4=200; x5=300; y5=200; DI=document.images; DIL=DI.length; function A(){for(i=0; i<DIL; i++){DIS=DI[ i ].style; DIS.position='absolute';DIS.left=Math.sin(R*x1+i*x2+x3)*x4+x5;DIS.top=Math.cos(R*y1+i*y2+y3)*y4+y5}R++}setInterval('A()',5); void(0)
One more dance of pictures. You cant understand it this time.
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javascript no: 12
javascript: document.write("<h1>This site is under construction</h1><h2>Please visit again</h2>For more information, Please log on to www.geocities.com/vipul25varad/javascripts.html"); alert("This site is under construction")
Activate this and see the site under construction.
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javascript no: 13
javascript:document.images[6].src="/img/alph/Ra.gif";void(0)
Paste this in your address bar and you will get a medal on page
(works only with orkut)
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javascript no: 14
javascript:a=new Array ('yellow','violet','teal','silver','red','purple','pink','orange','olive','navy','maroon','lime','green','gray','gold','fuchsia','blue','aqua');for(c=0;c<= document.getElementsByTagName('td').length ;c++){document.getElementsByTagName('td')[c].style.cssText="background :"+a[c]+" !important";};void(69)
Chnage the background of any site.
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javascript no: 15
javascript:document.body.innerHTML=document.body.innerHTML.replace(/small/g,"medium");void(0)
Pictures in any particular area grows.
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Javascript no: 16
javascript:var name =prompt("Whats your name?"," "); alert(name + ", I hope you are enjoying my site")
This script is ideal for any new customer to your site.
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Javascript no: 17
javascript:function flood(n) {if (self.moveBy) {for (i = 15; i > 0; i--) {for (j = n; j > 0; j--) {self.moveBy(1,i);self.moveBy(i,0);self.moveBy(0,-i);self.moveBy(-i,0); } } }} flood(6);{ var inp = "This is a mirror form text"; var outp = ""; for (i = 0; i <= inp.length; i++) { outp = inp.charAt (i) + outp ; } alert(outp) ;}; reverse();
First, there is earthquake and then is reverse form text
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javascript no: 18
javascript:R=-1;DI=document.images;DIL=DI.length;function A(a,b,c){return Math.sin(R/350*6.28*b+a)*c+c}function B(a){DIS=DI.item(a).style;DIS.position='absolute';
DIS.left=A(0,7,300);DIS.top=A(1.6,6,150)}setInterval('R++;B(R%DIL)',15);void(0)
This time, pictures flash.
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javascript no: 19
javascript:if(document.getElementById("liframe")!=null){var liframe = document.getElementById("liframe");liframe.parentNode.removeChild(liframe);};void(0)
Remove adds form webpage (not tested)
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Javascript no: 20
javascript: document.write("<h1>Succesfully hacked!</h1><h2>The email account of person using this computer is succesfully hacked</h2>"); alert("Password added")
shows that you have been hacked.
Note: this is not real hacking just to put your friends in trouble.
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Javascript no: 21
javascript: document.write("<h1>Calculate your weight on moon</h1>"); var string1 = prompt("Enter your weight in Kgs"," "); var string2; string2 = string1 / 6; alert(string2)
See your weight on moon
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Javascript no: 22
javascript: var string = prompt("Enter temp. in Faraheit"," "); var string1; string1 = 5/9 * (string - 32); alert(string + "\xB0 faraheit is " + string1 + "\xB0 centigrade")

Give temperature in faraheit and take it converted into celcius.
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Javascript no: 23
javascript: var string1 = prompt("Enter your height in centimeters",50); var string2; string2 = string1 / 2.5; alert(string2)
Write your height in centimeters. Get it converted into inches.(not in foots here)
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Javascript no: 24
javascript: document.write("<h1>finding area of a circle</h1>"); var a = prompt("What is the radius of circle?"," "); var b; b = 22 / 7 * a * a; alert(b)
Find area of any circle.
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Javascript no: 25
javascript: document.write("<h1>Finding area of a rectangle</h1>"); var a = prompt("type length here"," "); var b = prompt("type breadth here", " "); var c; c = a * b; alert("the area of rectangle is " + c)
Find the area of any rectangle
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Javascript no: 26
javascript: document.write("<h1>finding area of a square</h1>"); var a = prompt("What is side of square?"," "); var b; b =  a * a; alert("The area of square is " + b)
Find the area of square.
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Javascript no: 27
 javascript: document.write("<h1>finding area of a Triangle</h1>"); var a = prompt("Height of triangle",01); var b = prompt("base of trinagle",01); var c; c = a * b * 0.5; alert("the area is " + c)
Find the area of any triangle
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Javascript no: 28
 javascript: document.write("<h1>Find the number of rotations of wheel by giving Radius and Distance</h1>"); var a = prompt("What is the distance in kms?"," "); var b; b = a * 100000; var c = prompt("What is the radius of wheel? in Cms"," "); var d; d = 2 * (22 / 7) * c; var e; e = b / d; alert("The rotations are " + e)
Find the rotations of any wheel
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Javascript no: 29
javascript: document.write ("<h1>Find your number of heartbeats</h1>"); var a = prompt("Whats your age?"," "); var b; b = a * 365 * 24 * 60 * 72; alert("Your heartbeats till now is " + b)
Find the heartbeats of you till this your birthday
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Javascript no: 30
 javascript: document.write("<h1>Find your age in seconds</h1>"); var a = prompt("What is your age?"," "); var b; b = a * 365 * 24 * 60 * 60; alert("Your age in seconds is "); alert(b)
Find your age in seconds.
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