How to validate a number being an integer
Question
Recently I have been working on a "spinner" that increases and decreases a number by 1 each time, however I've wanted to add validation to the program so that integers only are accepted (no decimals) however I've been unsuccessful in doing this.
I've researched the use of NaN and parseValue(s) but I've not found a way of including this to my script, and any help would be highly appreciated. All code in the example given works as I want it to, therefore I only need the validation.
CODE: HTML
<!DOCTYPE html>
<html>
<head>
<h1>Spinners in JavaScript</h1>
</head>
<body>
<p id="textDisplay()">0</p>
<div align="middle">
<button onclick="spinUp()">+1</button>
<button onclick="spinDown()">-1</button>
</div>
</body>
</html>
JavaScript
currentNumber = 0;
function spinUp() {
if(currentNumber==100){
currentNumber = 0;
document.getElementById("textDisplay").innerHTML = currentNumber;
} else if(currentNumber < 100) {
currentNumber++
document.getElementById("textDisplay").innerHTML = currentNumber;
}
}
function spinDown() {
if(currentNumber>0){
currentNumber--;
document.getElementById("textDisplay").innerHTML = currentNumber;
} else if(currentNumber<=0){
window.alert("Too low! Higher!");
currentNumber++;
document.getElementById("textDisplay").innerHTML = currentNumber;
}
}
3 answers
solution1
1 2016-03-11 19:25:13
You could use a method like this:
if (number != Math.round(number)){
alert("Enter a whole number");
}
solution2
0 ACCPTED 2016-03-11 18:57:18
You can use the === operator as below :
if (data === parseInt(data, 10))
alert("data is integer")
else
alert("data is not an integer")
solution3
0 2016-03-11 19:45:53
v === v | 0;
如果 v 是整数，则为真，否则为假。
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