Simple Javascript Calculator
Question
I'm trying to learn Javascript and I feel like I have a decent grasp on the fundamentals but I am having problems making it do things that i want .. for example.. I am trying to create a simple form in html that calculates the sum of 2 numbers.. here is my html and javascript:
<head>
<script type="text/javascript">
function adder(a,b) {
var a = document.getElementById('firstNum').value;
var b = document.getElementById('secondNum').value;
var numbers = new Array(a,b);
var sum = 0;
for (i=0; i < numbers.length; i++) {
sum += parseInt(numbers[i]);
}
//this part i need help with
document.getElementById('answer').write("First Number: " + a + " plus Second Number: " + b + " is " + sum).value; //this part i need help with
</script>
</head>
<body>
<form id="additionForm">
A + B = C : <input type="text" id="firstNum" placeholder="A">
+ <input type="text" id="secondNum" placeholder="B">
<input type="button" id="addBtn" value="Add" onClick="adder();">
= <input type="text" id="answer" placeholder="C">
</form>
</body>
My problem is that i don't know how to get the javascript to overwrite the value attribute for my form input id=answer .. or if i'm supposed to be using Jquery instead .. thanks in advance.
2 answers
solution1
3 ACCPTED 2014-10-12 19:47:57
function adder() {
var a = parseInt( document.getElementById('firstNum').value, 10);
var b = parseInt( document.getElementById('secondNum').value, 10);
var sum = a + b;
//this part i need help with
document.getElementById('answer').value = "First Number: " + a + " plus Second Number: " + b + " is " + sum).value; //this part i need help with
}
solution2
2 2014-10-12 19:46:34
如果要修改javascript中的输入字段，只需设置value属性即可：
document.getElementById('answer').value = "First Number: " + a + " plus Second Number: " + b + " is " + sum;
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