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Math.random

Fire Dragon

By Fire Dragon
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Fire Dragon Member

Fire Dragon

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Hi!I create this kind code,but I want know one thing before I continue developing it.I want that code decreases one value,depend on what random value comes.

function decrease(){var value= Math.random()if (value<0.5){value2=value2 -10;}else{value2=value2 -20;}}

I have two questions.First,can you see any errors?Second question is about Math.random code.Like you see,this is function.If I create example button,and Math.random creates example value 0.42536.Than,I press again button.Question is,do math.random create new value?Example 0.84763.Thanks for help.I write this code to paper,and I can't test it yet,because it is part of huge code.I can't see any mistakes in it,but you can't never be sure... :) Thanks.

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scott100 Dedicated Member

scott100

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Math.random() always creates a new number, you can check this by putting it's result in an alert message. Also, if you put it within a Math.ceil() you get whole numbers ie 1 & 6 not 0.666 & 5.32656

<head><script>var value2=0;function decrease(){  var value=Math.ceil(Math.random()*10);  alert("Random number is "+value);    if (value<5)    {      value2=value2-10;      document.getElementById('val2').value=value2;    }    else    {      value2=value2-20;      document.getElementById('val2').value=value2;    }}</script></head><body><input type="button" value="button" onclick="decrease()" /><p>Value 2 <input type="input" value="0" id="val2" /></p></body>

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Fire Dragon Member

Fire Dragon

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Math.random() always creates a new number, you can check this by putting it's result in an alert message.  Also, if you put it within a Math.ceil() you get whole numbers ie 1 & 6 not 0.666 & 5.32656
<script>var value2=0;function decrease(){  var value=Math.ceil(Math.random()*10);  alert("Random number is "+value);    if (value<5)    {      value2=value2-10;      document.getElementById('val2').value=value2;    }    else    {      value2=value2-20;      document.getElementById('val2').value=value2;    }}</script><body><input type="button" value="button" onclick="decrease()" /><p>Value 2 <input type="input" value="0" id="val2" /></p></body>

I can't get it work.I tried modify and only copy & paste,but when I press button,I can't see any alerts,or field's value won't change.What I did wrong?
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scott100 Dedicated Member

scott100

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I can't get it work.I tried modify and only copy & paste,but when I press button,I can't see any alerts,or field's value won't change.What I did wrong?

What exactly did you "modify"? I don't know what's wrong unless you show me what changes you have made. :)
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Fire Dragon Member

Fire Dragon

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It's ok, these things happen!!  :)

Yeah,you are right :) By the way,I tried set that if value is 0 or less,code directes you to new URL,but I can't get it work right now.I tried if else statement,but I don't know why it wont work.Here is my code:
   else if (value<=0)   {     window.location("http://www.google.com")   }

I put it between if and else statements,but nothing happens when value is equal or under 0.What can be wrong?I also tried create own function,what checks value when user presses button,but it won't work.

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scott100 Dedicated Member

scott100

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By the way,I tried set that if value is 0 or less,code directes you to new URL,but I can't get it work right now.

That won't work because if you look at this line of code var value=Math.ceil(Math.random()*10); i used Math.ceil which rounds a number up to the nearest integer, it will never be 0.change it to Math.floor like so:
var value=Math.floor(Math.random()*10);

your if statement will now work for a 0. :)

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Fire Dragon Member

Fire Dragon

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Like usual,I can't get it work right now :) Here is my code:

<script>var value2=100;function decrease(){ var value=Math.floor(Math.random()*10); alert("Random number is "+value);   if (value<5)   {     value2=value2-10;     document.getElementById('val2').value=value2;   }     else if (value2<=0)  {    window.location("http://www.google.com")    document.getElementById('val2').value=value2;  }   else   {     value2=value2-20;     document.getElementById('val2').value=value2;   }}</script><body><input type="button" value="button" onclick="decrease()" /><p>Value 2 <input type="input" value="100" id="val2" /></p></body>

What is wrong now?I tried,but it doesn't activate window.location,even valu2 is 0 or less.

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scott100 Dedicated Member

scott100

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window.location("http://www.google.com") :) window.location="http://www.google.com" :D if (value<5) :) else if (value2<=0) :( if (value<5&&value>1) :) else if (value2==0) :blink:

<script>var value2=100;function decrease(){var value=Math.floor(Math.random()*10);alert("Random number is "+value);  if (value<5&&value>1)  {    value2=value2-10;    document.getElementById('val2').value=value2;  }    else if (value2==0) {   window.location="http://www.google.com";   document.getElementById('val2').value=value2; }  else  {    value2=value2-20;    document.getElementById('val2').value=value2;  }}</script><body><input type="button" value="button" onclick="decrease()" /><p>Value 2 <input type="input" value="100" id="val2" /></p></body>

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