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我想在表單中驗證輸入字段'putime',因爲即使'putime'輸入框爲空,結果也會計算,並且nightSurcharges也會添加到成本中。所以我想驗證'putime'是否爲空,否則腳本無用。在提交表單之前驗證輸入字段
function TaxiFare() {
// calculates taxi fare based upon miles travelled
// and the hour of the day in military time (0-23).
var baseFare = 14;
var costPerMile = 7.00;
var nightSurcharge = 20.50; // 9pm to 6am, every night //its flat 20.50 and not per mile
var milesTravelled = Number(document.getElementById("miles").value) || 0;
if ((milesTravelled < 1) || (milesTravelled > 200)) {
alert ("You must enter 1 - 200 miles");
document.getElementById("miles").focus();
return false;
}
var pickupTime = Number(document.getElementById("putime").value) || 0;
if ((pickupTime < 0) || (pickupTime > 23) || (pickupTime==null)) { // note the hours are 0-23. There is no 24 hour, midnight is 0 hours
alert ("The time must be 0-23 hours");
document.getElementById("putime").focus();
return false;
}
var cost = baseFare + (costPerMile * milesTravelled);
// add the nightSurcharge to the cost if it is after
// 8pm or before 6am
if (pickupTime >= 21 || pickupTime < 6) {
cost += nightSurcharge;
}
document.getElementById("result").innerHTML = "Your taxi fare is: $. " + cost.toFixed(2);
}
And here is the Form from HTML
<form>
Miles for Journey <input type="text" id = "miles" required><br>
Pickup Time <input type = text id = "putime" required><br><br>
<input type="button" value="Calculate Fare" onclick="TaxiFare()">
<input type="reset" value="Clear"><br><br>
<span id = "result"></span>
</form>
我試了很多,但無濟於事....任何幫助是歡迎的。提前致謝!