Very new to Javascript

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joeyjj

Hello,

I'm trying to use Javascript to enhance a few features of my site.
I've wrote a fewlines that will convert two textboxes between cm and inches interchangeably.

However, I would also like to round the result to make it easier to read.

i.e. Entering Inches = 1.4
Yields cm = 3.5559999999999996
Whereas it should really read cm = 3.556, or even 3.56

In the code below I tried changing the line

ONKEYUP="document.convert.ins.value = (1/2.54) * document.convert.cms.value" 

to

ONKEYUP="document.convert.ins.value = Math.round((1/2.54) * document.convert.cms.value)"

Here's my code:

 <FORM ACTION="#" NAME="convert" >
Enter Inches
<INPUT TYPE=TEXT NAME="ins"
    ONKEYUP=" document.convert.cms.value = 2.54 * document.convert.ins.value" 

>
<BR><BR>
<INPUT TYPE=TEXT NAME="cms" 
    ONKEYUP="document.convert.ins.value = (1/2.54) * document.convert.cms.value" 

>
centimetres
</FORM>

Thanks in advance!

007Julien

To work with numbers use

var rndValue=math.round(100*value)/100;

But to build a string prefer :

var rndString=value.toFixed(2);

joeyjj

007Julien;1271651 wrote:
To work with numbers use
var rndValue=math.round(100*value)/100;
But to build a string prefer :
var rndString=value.toFixed(2);

Thanks for the help, but I'm still too new to work that out. I've tried it in numerous places inside my code, but I can't get it to work sorry.

joeyjj

Thanks, I've solved it now.

Padonak

a hint: if Julien saw your code the help could be much more efficient

Ay__351_e

 
<html>
<head>

<script type="text/javascript">
// http://www.webdeveloper.com/forum/showthread.php?279263-Very-new-to-Javascript
// http://www.w3schools.com/jsref/jsref_unshift.asp
// http://www.w3schools.com/jsref/jsref_obj_array.asp
// http://www.w3schools.com/jsref/jsref_obj_string.asp
// http://www.w3schools.com/jsref/jsref_charat.asp
// http://www.w3schools.com/jsref/jsref_obj_regexp.asp



// çarpma i&#351;lemi
// multiplication

// çarpma i&#351;lemini yapmaya ba&#351;layal&#305;m

function multiplication(num, num2, dec) { 
// alert(' ba&#351;taki dec = '+dec);
// dizilerin eleman say&#305;lar&#305; ayn&#305; de&#287;ilse, dizinin ba&#351; k&#305;sm&#305;na 0 ekleyerek, eleman say&#305;lar&#305;n&#305; ayn&#305; yapal&#305;m.
while(num.length > num2.length) { num2.unshift(0); }
while(num2.length > num.length) { num.unshift(0); }

var netice = [];
var i, k, t, basamak, elde = 0, L = num.length -1;
for(i=L; i>=0; i--)  {
basamak = elde;

 t=i;
for(k = L; k>=i; k--) {
 basamak += num[k] * num2[t]; 
 t++;
 }
if(basamak>9) { elde =   parseInt(basamak/10);   netice.unshift(basamak % 10); }
if(basamak < 10) { elde = 0; netice.unshift(basamak) ; }
}

var p, r = L - 1, u = r, y;
for( p= r; p >=0; p--) {
y=p;
 basamak = elde;
  for( m = 0; m<=p; m++) {
 basamak += num[m] * num2[y];  y--;  

}

if(basamak>9) { elde =   parseInt(basamak/10);  netice.unshift(basamak % 10); }
if(basamak < 10) { elde = 0; netice.unshift(basamak) ; }

}

if(elde > 0) { 
netice.unshift(elde); 
}
// dizide hangi say&#305;dan önce nokta olmas&#305; gerekti&#287;ini belirleyelim.
if(dec > 0 ) {  var say = netice.length - dec;  netice[say] =  '.'+ netice[say]; }

// diziyi stringe çevirelim. Ba&#351; k&#305;s&#305;mda 0 var ise bunlar&#305; atal&#305;m.
var s = netice.join('').replace(/^0+/,'');
//alert('s = '+ s); 
return s;

}



function bul() {

var el = document.convert.ins.value;

// metin kutusuna say&#305; girip girmedi&#287;ini kontrol edelim
var re = /^\d+(\.\d+)?$/;
// alert(re.test(el));
if(re.test(el)== false) { alert('enter a number  (1.4  or 14 )'); return false;}

var A = []; // bu dizinin içine, metin alan&#305;na girilen say&#305;y&#305; yerle&#351;tirece&#287;iz

var dec=0; // ondal&#305;k basamak say&#305;s&#305;
var i;


 for( i=0; i<el.length; i++) { 
  if(el.charAt(i) != '.') { A[A.length] =  el.charAt(i); }
  if(el.charAt(i) == '.'){ dec = el.length - (i+1); }
 }
//alert('A =  '+A);
//alert('dec = '+dec);
var B = [2,5,4]; // 2.54 say&#305;s&#305;ndaki rakamlar&#305; s&#305;rayla dizi içine yerle&#351;tirdik
dec = dec + 2 ; // 2.54 say&#305;s&#305;nda iki tane ondal&#305;k basamak var. Onu da ekleyelim 

//alert('dec = ' + dec);


var result = document.convert.cms;
result.value = multiplication(A, B, dec);

}

</script>

</head>
<body>
 <FORM ACTION="#" NAME="convert" >
Enter Inches
<INPUT TYPE=TEXT NAME="ins"><BR><BR><input type="button" value="convert" onclick='bul()'>
<BR><BR>
<INPUT TYPE=TEXT NAME="cms" readonly> centimetres
</FORM>
</body>
</html>