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A simple calculator written in JavaScript

Source: Internet
Author: User
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Teacher decorate the task, get a day, finally put out the code, as rookie give himself a little applause, legend JS is very simple, but to write a program really need exercise, my exercise is too little, every day DotA. Hehe (made a little comment) you should be able to read it (no annotated program I don't like)

Those who wish to see have some advice. In addition Eval_r to Eval, a total of 4 (do not know why this occurs after saving)



<title> Web Calculator bywillikan</title>
<meta name= "Willikan" >
<body>
<script language= "JavaScript" >
<!--Hide the script from old browsers--
var a= ""//Store first operand
var b= ""//Store second operand
var x= ""//Store symbol
var c= ""//Store results
var i=0//judgment is the number of operands
var j=0//Determine if the first operand has a previous result
var k=0//judgment equals number arithmetic rule
var l=0//0 flag before the second operand
function Enter (obj,string)//Input character method
{if (J==1&&l==1///) clears the input second operand as the first operand according to the J-value decision result
{obj.expr.value= ""}
if (i==0)//The first operand is entered as determined by the I value
{Obj.expr.value + = string
A=0
J=0
}
else//Otherwise the second operand, empty the input
{
Obj.expr.value=obj.expr.value+string
B=obj.expr.value
A=a+string
L=0
}
}

function enters (obj,string)//Symbol input functions "+-*/%"
{a=obj.expr.value//a get first operand
A+=string//a to get the symbol again
x=string//x Get symbol
I=1//post-change flag the number of operands followed must be the second operand
J=1//result is the first operand
K=1//continues to use the flags of the X and the second operands. Always press the ' = ' case
L=1
}

function enterS1 (obj)//symbol for open radical
{A=obj.expr.value
var t=math.sqrt (parseint (A))
Obj.expr.value=t
}

function enterS2 (obj)//functions with symbol squared
{A=obj.expr.value
var T=math.pow (parseint (A), 2)
Obj.expr.value=t
}

function enterS3 (obj)//functions that resolve the sign
{A=obj.expr.value
var t=0-parseint (A)
Obj.expr.value=t
}

Use of function enterS4 (obj)//c backspace

{var a=obj.expr.value.split ("")

Obj.expr.value= ""

for (Var i=0;i<a.length-1;i++)

{Obj.expr.value+=a[i]}
}

function compute (obj)//equals sign execution
{if (k==0)
{A=c+x+b
Obj.expr.value=eval_r (A)//eval function directly numerical calculation of character channeling
C=eval_r (A)
}
Else
{obj.expr.value = Eval_r (A)
C=eval_r (A)
K=0
}
}

function Clearp (obj)//emptying functions for C or CE
{Obj.expr.value = ""
I=0
J=0
K=0
}

</script>
<center>
<form name= "Calc" >
<table border=1 algin= "center" >

<TR><TD colspan=3><input type= "text" name= "expr" size=30 action= "compute (this.form)" >
<td><input type= "button" value= "C" onclick= "enterS4 (this.form)" >
<td><input type= "button" value= "CE" onclick= "Clearp (this.form)" >

<tr><td><input type= "button" value= "7" onclick= "Enter (This.form, ' 7 ')" >
<td><input type= "button" value= "8" onclick= "Enter (This.form, ' 8 ')" >
<td><input type= "button" value= "9" onclick= "Enter (This.form, ' 9 ')" >
<td><input type= "button" value= "/" onclick= "enters (this.form, '/')" >
<td><input type= "button" value= "sqrt" onclick= "enterS1 (this.form)" >

<tr><td><input type= "button" value= "  4  " onclick= "Enter (This.form, ' 4 ')"
<td><input type= "button" value= "  5  " onclick= "Enter (This.form, ' 5 ')" >
<td><input type= "button" value= "  6  " onclick= "Enter (This.form, ' 6 ')";
<td><input type= "button" value= "  *  " onclick= "enters (this.form, ' * ')";
<td ><input type= "button" value= "  sqr  " onclick= "enterS2 (this.form)";

<tr><td><input type= "button" value= "  1  " onclick= "Enter (This.form, ' 1 ')"
<td><input type= "button" value= "  2  " onclick= "Enter (This.form, ' 2 ')" >
<td><input type= "button" value= "  3  " onclick= "Enter (This.form, ' 3 ')";
<td><input type= "button" value= "  -  " onclick= "enters (this.form, '-')";
<td ><input type= "button" value= "   %   " onclick= "enters (this.form, '% ')";

<tr><td><input type= "button" value= "0" onclick= "Enter (This.form, ' 0 ')" >
<td><input type= "button" value= "+/-" onclick= "enterS3 (this.form)" >
<td><input type= "button" value= ". "Onclick=" Enter (This.form, '. ') " >
<td><input type= "button" value= "+" onclick= "enters (this.form, ' + ')" >
<td><input type= "button" value= "=" onclick= "Compute (this.form)" >

</table>

</form>
</center>
</body>

A simple calculator written in JavaScript

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