CODEWITHSUNDEEP
javascriptarraysdynamictextboxaddition
Nditah
Nditah

Reputation: 1739

Add the Values of Text boxes dynamically with Javascript

I Expect to get the sum when I click the button but nothing happens. This is however the simplified version of the code I want to use. The values of the textboxes are actually being queried from a database with php. Please F1. Here is the complete code.

<html>
<head>
</head>
<body>
<h1> JavaScript </h1>
<script type="text/javascript">
// Addint an array of values from a text box
function calc(){
    var mutli_Credit = document.course_reg.elements['Credit[]'];
    var sum = 0, i = 0, len = mutli_Credit.length;
    for(i < len; ++i){
    sum += parseInt(document.getElementById('Credit[i]).value, 10); 
    // Use parseFloat if you're dealing with floating point numbers.
    }
    //alert(sum);   
    document.getElementById('credit_load').value = sum;
    };

</script>
<form name='course_reg' onLoad=''>
MATH101 <input type='text' name='Credit[]'  value='3' id='Credit[]' size='3' readonly /><br/>
CSC201 <input type='text' name='Credit[]'  value='2' id='Credit[]' size='3' readonly /><br/>
EDU301 <input type='text' name='Credit[]'  value='2' id='Credit[]' size='3' readonly /><br/>
<BUTTON onClick='calc()'> CALCULATE </BUTTON>
Total Credit Load:<input type='text' value='' id='credit_load' name='credit_load' size='3'  readonly/></p>

</form>
</body>
</html>

Upvotes: 0

Views: 1665

Answers (2)

nanndoj
nanndoj

Reputation: 6770

Your code is full of mistakes. I fixed it for you to use as base

Add a class to all input elements you want to sum, never use the same ID to different elements and add a class to all inputs you want to sum;

MATH101 <input type='text' name='Credit0'  value='3' id='Credit0' class="sumInput" size='3' readonly /><br/>
CSC201 <input type='text' name='Credit1'  value='2' id='Credit1' class="sumInput" size='3' readonly /><br/>
EDU301 <input type='text' name='Credit2'  value='2' id='Credit2' class="sumInput" size='3' readonly /><br/>

Retrieve all input elements

var mutli_Credit = document.getElementsByTagName("input");

Fix your for statement by initializing the variable

for(var i = 0; i < len; ++i){

Check if the element has the ID you gave them

if(mutli_Credit[i].className === "sumInput")

Sum the elements

sum += parseInt(mutli_Credit[i].value);

This is the fixed code:

// Addint an array of values from a text box 
function calc(){
    var mutli_Credit = document.getElementsByTagName("input");
    var sum = 0, i = 0, len = mutli_Credit.length;
    for(var i = 0; i < len; ++i){
      if(mutli_Credit[i].className === "sumInput") {
        sum += parseInt(mutli_Credit[i].value);
      }
    }
    document.getElementById('credit_load').value = sum;
};

...

MATH101 <input type='text' name='Credit0'  value='3' id='Credit0' class="sumInput" size='3' readonly /><br/>
CSC201 <input type='text' name='Credit1'  value='2' id='Credit1' class="sumInput" size='3' readonly /><br/>
EDU301 <input type='text' name='Credit2'  value='2' id='Credit2' class="sumInput" size='3' readonly /><br/>
<BUTTON onClick='calc()'> CALCULATE </BUTTON>
Total Credit Load:<input type='text' value='' id='credit_load' name='credit_load' size='3'  readonly/></p>

Upvotes: 0

DoctorMick
DoctorMick

Reputation: 6793

Problem 1 - you need to initialise the counter variable in the for loop.

for(i = 0; i < len; ++i){

Problem 2 - the way you're trying to get an element using it's index is incorrect, you should be using the array of elements you grabbed at the top.

sum += parseInt(mutli_Credit[i].value, 10);

Problem 3 - you're not returning anything from your function so the page refreshes.

function calc(){
    ....
    return false;
};

<BUTTON onClick='return calc()'> CALCULATE </BUTTON>

And remove the duplicate ids.

Upvotes: 1

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