通过获取 html（货币转换器）的 select 标记来乘以 javascript 中的不同值

Question

I want to make a currency convert. mean using select tag of html select different currency and multiply with input value using javascript

 function getInputValue(){ // Selecting the input element and get its value var inputVal = document.getElementById("myInput").value=currency; var dollar = inputVal*1.12; var answer = document.getElementById('answer'); answer.value= dollar; var inputVal = document.getElementById("myInput").value=currency; var pound = inputVal*0,86; var answer = document.getElementById('answer'); answer.value= pound; var inputVal = document.getElementById("myInput").value=currency; var pak = inputVal*170; var answer = document.getElementById('answer'); answer.value= pak; } function newVal(){ document.getElementById("myForm").reset(); }

 <select id="currency"> <option value="volvo" >Doller</option> <option value="volvo">Pound</option> <option value="volvo">Pak</option> </select>

Answer 1

A nice approach would be to use each option's value to hold the currency's exchange rate, like so:

<select id="currency">
    <option value="1.12" >Dollar</option>
    <option value="0.86">Pound</option>
    <option value="170">Pak</option>
</select>

Then, in your Javascript function, you can simply multiply the amount by the selected option's value attribute:

function getInputValue(){
    //assuming you are typing the amount in an input with id "myInput"
    var amount = document.getElementById("myInput").value; 
    var rate = document.getElementById("currency").value;
    var result = amount * rate;

    //output the result to HTML
    //(assuming you have a div or element with id "result")
    document.getElementById("result").innerHTML = result;
}

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On a side note, in your original code, I am not sure what you were trying to do with:

var inputVal = document.getElementById("myInput").value=currency;

Did you mean to real the value of currency ? Then you should have done:

var inputVal = document.getElementById("currency").value;