Here is a really simple JavaScript calculator – with just 5 functions! (Add, subtract, multiply, divide, and power) This example can help you see how JavaScript evaluates math functions! Check it out!

 

<!-- TWO STEPS TO INSTALL 5 FUNCTION CALCULATOR:
 
   1.  Paste the coding into the HEAD of your HTML document
   2.  Add the last code into the BODY of your HTML document  -->
 
<!-- STEP ONE: Copy this code into the HEAD of your HTML document  -->
 
<head>
 
<script LANGUAGE="JavaScript">
 
<!-- Original: Rick Johnson -->
<!-- Web Site:  http://members.tripod.com/~RickJohnson -->
 
<!--Total Java Scripts 99 - Next Step Software-->
 
<!-- Begin
function a_plus_b(form) {
a=eval(form.a.value)
b=eval(form.b.value)
c=a+b
form.ans.value = c
}
function a_minus_b(form) {
a=eval(form.a.value)
b=eval(form.b.value)
c=a-b
form.ans.value=c
}
function a_times_b(form) {
a=eval(form.a.value)
b=eval(form.b.value)
c=a*b
form.ans.value=c
}
function a_div_b(form) {
a=eval(form.a.value)
b=eval(form.b.value)
c=a/b
form.ans.value = c
}
function a_pow_b(form) {
a=eval(form.a.value)
b=eval(form.b.value)
c=Math.pow(a, b)
form.ans.value = c
}
// End -->
</script>
 
<!-- STEP TWO: Put this code into the BODY of your HTML document  -->
 
<body>
<center>
<form name="formx"><input type=text size=4 value=12 name="a">
<input type="button" value="  +  " onClick="a_plus_b(this.form)">
<input type="button" value="  -  " onClick="a_minus_b(this.form)">
<input type="button" value="  x  " onClick="a_times_b(this.form)">
<input type="button" value="  /  " onClick="a_div_b(this.form)">
<input type="button" value="  ^  " onClick="a_pow_b(this.form)">
<input type="number" size=4 value=3 name="b"> = <input type "number" value=0 name="ans" size=9>
</form>
</center>
 
<!-- Script Size:  1.72 KB  -->