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JS to implement a simple calculator

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Author: User
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use JS to complete a simple calculator function. After you have entered an integer into the 2 input boxes, click on the third input box to give a subtraction of 2 integers. Effect as above:

The first step: Create the build Operation function count ().

Step two: Get the values in the two input boxes and get the value of the selection box.

Hint: document.getElementById (id name). Value Gets or sets the value of the ID name.

Step three: Get the value selected by the drop-down box to change the subtraction algorithm.

Tip: Use switch to determine the algorithm.

Fourth step: Call the Created function with the = button to get the result.

Note: use the parseint () function to parse a string and return an integer.

Code:

1 <!DOCTYPE HTML>2 <HTML>3  <Head>4   <title>Event</title>  5   <Scripttype= "Text/javascript">6    functioncount () {7     vara=document.getElementById ("txt1"). Value;8     varb=document.getElementById ("txt2"). Value;9     //gets the value of the first input boxTen     //gets the value of the second input box One     //gets the value of the selection box A     varC=document.getElementById ("Select"). Value; - a=parsefloat (a); - b=parsefloat (b); the     //gets the value selected by the drop-down box to change the subtraction algorithm -     //set the value of the result input box -     Switch(c) { -          Case "+": + document.getElementById ("Fruit"). Value=parseint (a)+parseint (b); -          Break; +          Case "-": A document.getElementById ("Fruit"). Value=parseint (a)-parseint (b); at          Break; -          Case "*": - Ocument.getelementbyid ("Fruit"). Value=parseint (a)*parseint (b); -          Break; -          Case "/": - document.getElementById ("Fruit"). Value=parseint (a)/parseint (b); in          Break; -     } to    } +   </Script>  -  </Head>  the  <Body> *    <inputtype= ' text 'ID= ' Txt1 '/>  $    <SelectID= ' SELECT '>Panax Notoginseng         <optionvalue="+">+</option> -         <optionvalue="-">-</option> the         <optionvalue="*">*</option> +         <optionvalue="/">/</option> A    </Select> the    <inputtype= ' text 'ID= ' txt2 '/>  +    <inputtype= ' button 'value= ' = 'onclick= "count ()"/> -    <inputtype= ' text 'ID= ' Fruit '/>    $  </Body> $ </HTML>

JS to implement a simple calculator

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