[英]How to make alert box and innerHTML show in javascript
我正在嘗試使用簡單的javascript字段驗證器制作工資計算器。 但是,當我添加條件if語句時,它們似乎相互抵消了。 我不確定我是否需要制作另一個功能來實現這一目標。
function myFunction() { var rate = document.getElementById("payrate").value; var hours = document.getElementById("hours").value; var salary; salary = rate * hours; if (hours == ' '){ alert("Fill hours"); else if (payrate == ' '){ alert("Fill payrate"); } } if (salary < 20000) { salary = "The salary is too little"; }else if(salary > 20000 && salary < 25000){ salary = "Let's negotiate"; } else { salary = "This good salary"; document.getElementById("demo").innerHTML = salary; } }
<p id="demo"></p> Enter hourly Rate: <input type="text" id="payrate"><br> Enter hours: <input type="text" id="hours"><br> <input type="submit" value="Yearly Salary" onclick="myFunction()">
這里有4個問題:
rate
但檢查變量名稱payrate
。 ' '
)時有空格。 這會導致錯誤的結果。 ''
應該用來代替。 但是,我建議在我的代碼中采用另一種方式。 所以,新代碼是:
function myFunction() {
var rate = document.getElementById("payrate").value;
var hours = document.getElementById("hours").value;
var salary;
// Validate data first
if (!hours) {
alert("Fill hours");
// Stop the execution
return false;
} else if (!rate) {
alert("Fill payrate");
// Stop the execution
return false;
}
salary = rate * hours;
if (salary < 20000) {
salary = "The salary is too little";
} else if (salary > 20000 && salary < 25000) {
salary = "Let's negotiate";
} else {
salary = "This good salary";
}
document.getElementById("demo").innerHTML = salary;
}
您的括號未正確關閉。
嘗試這個:
function myFunction() {
var rate = document.getElementById("payrate").value;
var hours = document.getElementById("hours").value;
var salary;
salary = rate * hours;
if (hours == ' ') {
alert("Fill hours");
}
else if (payrate == ' ') {
alert("Fill payrate");
}
if (salary < 20000) {
salary = "The salary is too little";
} else if(salary > 20000 && salary < 25000){
salary = "Let's negotiate";
} else {
salary = "This good salary";
}
document.getElementById("demo").innerHTML = salary;
}
你的邏輯很糟糕,括號沒有正確關閉試試這個:
function myFunction() {
var rate = document.getElementById("payrate").value;
var hours = document.getElementById("hours").value;
var salary;
salary = rate * hours;
//With out reurn false; the flow will still continue and return an value in the demo
// and also check for if hours is a number
if (hours === '' || isNaN(hours)){
alert("Fill hours");
return false;
}
//With out reurn false; the flow will still continue and return an value in the demo
// and also check for if payrateis a number.
if (payrate === '' || isNaN(payrate) ){
alert("Fill payrate");
return false;
}
if (salary < 20000) {
salary = "The salary is too little";
}else if(salary > 20000 && salary < 25000){
salary = "Let's negotiate";
} else {
salary = "This good salary";
}
document.getElementById("demo").innerHTML = salary;
}
在'if'語句中,你有像salary = "The salary is too little"
。 也許你打算做一些像console.log("The salary is too little")
這樣的事情console.log("The salary is too little")
? 或者您可以使用警報而不是console.log。 希望有效。
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