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Implementation of the 9.JavaScript simple calculator

Source: Internet
Author: User
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1. Difficulty, how to get the value of the tag, note that the obtained value is a string type, but also to convert

var num1 = parseint (document.getElementById ("NUM1"). Value);
var num2 = parseint (document.getElementById ("num2"). Value);

2. How to get the value under the Select drop-down menu:

Here said my own Baidu came.

var tag = document.getElementById ("Myselect");
alert (tag);
Get the value of a label
var opeartor = Tag.options[tag.selectedindex].value;

Implementation code:

<!DOCTYPE HTML><HTMLLang= "en"><Head>    <MetaCharSet= "UTF-8">    <title>Calculator implementation</title>    <Scripttype= "Text/javascript">        functionOpera () {varNUM1=parseint (document.getElementById ("NUM1"). Value); varnum2=parseint (document.getElementById ("num2"). Value); varTag=document.getElementById ("Myselect"); //alert (tag);            //get the value of a label            varOpeartor=Tag.options[tag.selectedindex].value; //alert (opeartor);         //alert (NUM1);            //alert (num2);            //declaring variables to store values            varresult= 0; Switch(opeartor) { Case "+": Result=NUM1+num2; //alert (' Test ');                     Break;  Case "-": Result=NUM1-num2; //alert (' msg ');                     Break;  Case "*": Result=NUM1*num2;  Break;  Case "/": Result=NUM1/num2;  Break; }            //alert (result);            //alert (' msg ');
Assigns a value to the label of id= "result"document.getElementById ("result"). Value=result; }    </Script></Head><Body>    <H1>Calculator implementation</H1>    <inputtype= "text"ID= "NUM1" />    <SelectID= "Myselect">        <optionvalue="+"ID="+">+</option>        <optionvalue="-"ID="-">-</option>        <optionvalue="*"ID="*">*</option>        <optionvalue="/"ID="/">/</option>    </Select>    <inputtype= "text"ID= "Num2" />    =    <inputtype= "text"ID= "Result"onclick= "Opera ()"></Body></HTML>

Implementation of the 9.JavaScript simple calculator

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