I have been looking to validate the data input to check whether it is a integer or a string. I looked around and saw some suggestions and typeof suggestions but nothing seems to work.
var nam = prompt("Enter name:")
person.push(nam);
var mk1 = prompt("Enter mark 1:");
var mk1 = parseInt(mk1);
mark1.push(mk1);
If you want to check whether input string is not a number try this:
if (isNaN(parseInt(name, 10)) {
//name is String
} else {
//name is Number
}
use the === operator as below
if (mk1 === parseInt(mk1 , 10))
alert("mk1 is integer")
else
alert("mk1 is not an integer. May be String")
If you don't know that the argument is a number-
function isInt(n){
return Number(n)===n && n%1===0;
}
Try this way to find input type;
if(!isNaN(parseInt(mk1)))
// for integer
else if(!isNaN(parseFloat(mk1)))
//for float
else
// String
When you prompt() the user for data, you always get a string. If you want to check, whether it actually contains just a number, you can try this:
var value = prompt('...'),
num = parseInt(value, 10);
if (num == value) {
// ... it is an integer, use `num`
} else {
// ... it's not an integer (or not *just* an integer), use `value`
}
(or use parseFloat(value) for real numbers).
It's hard to say what are you trying to do really. You seem to declare var mk1 twice, which looks a bit strange. Also, even if parseInt fails (then returns NaN [Not a Number]) you add it to mark1, which is probably not what you want. Have a look at this:
var nam = prompt("Enter name:")
person.push(nam);
var mk1 = prompt("Enter mark 1:");
mk1 = parseInt(mk1);
if (Number.isNaN(mk1) === false) {
mark1.push(mk1);
} else {
alert("mark 1 is not a number");
}
Use this function:
isNaN(parseInt(mk1))
It will return "true" if not a number, and "false" if a number
Related
I am defining a function that takes three numbers as arguments and returns the largest of them.
Here is my code:
var instructions = alert("Choose a set of numbers to input for the computer to determine which value is the largest");
var inputOne = prompt("Please input your first desired value");
var inputTwo = prompt("Please input your second desired value");
// THIS ARRAY STORES THE VALUES OF inputOne && inputTwo
var maxInput = Math.max([inputOne, inputTwo]);
var inputThree = prompt("Please input your third desired value");
// THIS WILL COMPARE BETWEEN THE inputThree && THE MAX INPUT OF THE USERS FIRST TWO CHOICES
var maxNumber = Math.max(maxInput, inputThree);
//validate if inputs are numbers and not letters
// isNaN()
var compare = function (maxNumber, inputThree) {
if (inputThree === maxNumber) {
return alert("The result is the same!");
} else if (inputThree != maxNumber) {
return alert(maxNumber + " " + "is the larger value!");
}
}
compare(maxNumber, inputThree);
Now I'm getting a result of "NaN is the larger value!" and it's driving me crazy! I tried running console.log to see where I'm getting NaN but that didn't work at all. All that did was log NaN to the console.
I also tried taking the parameters out of Math.max( ) however was just getting:
"-infinity is the larger value!"
Can someone at least give me a hint as to why this is happening? Or explain to me further what is going on.
Math.max([inputOne, inputTwo]) should be Math.max(inputOne, inputTwo)
Why don't you just get the largest of all of them with just
var maxNumber = Math.Max(inputOne, inputTwo, inputThree);
Here:
var inputThree = prompt("Please input your third desired value");
inputThree is a String (i.e. its value has a Type of String), always. And here:
var maxNumber = Math.max(maxInput, inputThree);
maxNumber is a Number, always (because that's what Math.max returns, even though the arguments are Strings). So:
inputThree === maxNumber
is always false, because a Number is never equal to a String (see the Strict Equality Comparison Algorithm). So either convert inputThree to a Number, e.g.
+inputThree === maxNumber
or use ==.
inputThree == maxNumber
Here is my jsFiddle
Its on the Phone method, no the name one
Now is this line right? I only want it to be true if the first 3 letters are 087
var RightStarting3 = value.substring(0,2) == (087);
if (BlankPass || LessThan10 || RightStarting3 || GreaterThan10 || (HasSpaces > 0))
{
document.getElementById('Phone').style.background = "red";
return false;
}
else {
document.getElementById('Phone').style.background = "white";
document.getElementById("PhoneTick").style.visibility="visible";
return true;
}
var RightStarting3 = value.substring(0,3) === ('087');
value.substring(x) returns a string and 087 and 87 mean the same to javascript interpreter. You should change one of the datatypes so that they match...
Either the substring to an integer:
var RightStarting3 = parseInt(value.substring(0,2)) == 87;
Or the value you're comparing against to a string:
var RightStarting3 = value.substring(0,3) == "087";
Secondly -- you are invoking ValidateName() immediately (in your assignment to NamePass). Is this really necessary? There will be empty values on page load.
I think with the javascript substring(x,y) method, the y value is the value at which to stop the selection. So in your example the first 3 characters will not be selected and instead the first 2 characters will be selected.
var a = "123";
// this returns "12"
alert(a.substring(0,2));
You probably want to use var RightStarting3 = value.substring(0,3) == ('087'); instead.
KingKongFrom's answer is correct, I would add that you should make sure that value (whatever that is) isn't null first, cause if you try to call substring on null it will thrown an exception and die.
I'm trying to validate a form input value. The function below states is the value of the input is a number below 150, show error. Works as it should. However, I want to add to it. If the value contains ANYTHING other than a numeric value AND/OR is a value under 150, show error...
How can I modify?
if ($('.billboard-height').val() < 150) {
$('.sb-billboardalert').fadeIn(600);
}
Since your more thorough validation should be on the server-side anyway, you could just use parseInt or parseFloat depending on what sort of value you are expecting. Then check if the result is actually a number and that it also meets your constraints:
var number = parseFloat($('.billboard-height').val()); // or parseInt depending on expected input
if (isNaN(number) || number < 150) {
$('.sb-billboardalert').fadeIn(600);
}
EDIT:
Based on your comments, you are entering regex land. I gather you only ever want a natural number (and the way parseInt/parseFloat ignores trailing non-numeric characters like px, em, etc. is not ok). How about:
var val = $('.billboard-height').val();
var number = parseInt(val, 10);
if ( ! val.match(/^[0-9]{3,4}$/) || number < 150) {
$('.sb-billboardalert').fadeIn(600);
}
This should only allow natural numbers 150-9999.
I would suggest using regexes:
var intRegex = /^\d+$/;
var floatRegex = /^((\d+(\.\d *)?)|((\d*\.)?\d+))$/;
var str = $('#myTextBox').val();
if(intRegex.test(str) || floatRegex.test(str)) {
alert('I am a number');
...
}
Or with a single regex as per #Platinum Azure's suggestion:
var numberRegex = /^[+-]?\d+(\.\d+)?([eE][+-]?\d+)?$/;
var str = $('#myTextBox').val();
if(numberRegex.test(str)) {
alert('I am a number');
...
}
ref: checking if number entered is a digit in jquery
Don't forget the radix parameter in parseInt():
if (parseInt($('.billboard-height').val(), 10) < 150) {
It's probably faster than using a regex. Regular expressions are not known for being fast, but they are very powerful. It might be overkill for this scenario.
You can try out HTML5's built in form validation:
<input type="number" min="150">
browser support is still pretty shakey though
Any value from an input or select will be a string in javascript. You need to use parseInt() to use operators like > or <. == can be used if you use it to compare to a string like if ($('.billboard-height').val() == "150")
Try parseInt and isNaN functions for check if value is number and less than 150:
var intVal = parseInt($('.billboard-height').val());
if(!isNaN(intVal)){ //not Number
if (parseInt($('.billboard-height').val()) < 150) { //not less than 150
$('.sb-billboardalert').fadeIn(600);
}
}
If you need to support floating point numbers, you can check if a variable is valid using:
function isNumber (n) {
return !isNaN(parseFloat(n)) && isFinite(n);
}
var val = $('.billboard-height').val();
if (isNumber(val) && parseFloat(val) < 150) {
$('.sb-billboardalert').fadeIn(600);
}
If you only need to support integers, use parseInt(n, 10), where 10 is the base to convert the string to.
var val = parseInt($('.billboard-height').val(), 10);
if (val && val < 150) {
$('.sb-billboardalert').fadeIn(600);
}
// Displays an alert if s contains a non-numeric character.
function alertForNonNumeric(s) {
var rgx = /[^0-9]/;
if (s.search(rgx) !== -1) {
alert("Input contains non-numeric characters!");
}
}
JS Fiddle here
NOTE: If you want to check for negative ints as well, you can add a minus sign to the regex:
function alertForNonNumeric(s) {
var rgx = /[^0-9-]/;
if (s.search(rgx) !== -1) {
alert(s + " contains non-numeric characters!");
}
}
I use this solution, I find it quite ellegant - no alerts, user is effectively unable to enter non numeric characters.
This is jQuery example:
function digitsOnly(){
// extract only numbers from input
var num_val = $('#only_numbers').val().match(/\d+/);
$('#only_numbers').val(num_val);
}
Your html:
<input type="text" name="only_numbers" id="only_numbers" on oninput="digitsOnly();"/>
I have scenario where if user enters for example 000.03, I want to show the user it as .03 instead of 000.03. How can I do this with Javascript?
You can use a regular expression:
"000.03".replace(/^0+\./, ".");
Adjust it to your liking.
This actually is trickier than it first seems. Removing leading zero's is not something that is standard Javascript. I found this elegant solution online and edited it a bit.
function removeLeadingZeros(strNumber)
{
while (strNumber.substr(0,1) == '0' && strNumber.length>1)
{
strNumber = strNumber.substr(1);
}
return strNumber;
}
userInput = "000.03";
alert(removeLeadingZeros(userInput));
How about:
function showRounded(val) {
var zero = parseInt(val.split('.')[0],10) === 0;
return zero ? val.substring(val.indexOf('.')) : val.replace(/^0+/,'') );
}
console.log(showRounded('000.03')); //=> ".03"
console.log(showRounded('900.03')); //=> "900.03"
console.log(showRounded('009.03')); //=> "9.03"
Or adjust Álvaro G. Vicario's solution to get rid of leading zero's into:
String(parseFloat("090.03")).replace(/^0+\./, ".")
This function will take any string and try to parse it as a number, then format it the way you described:
function makePretty(userInput) {
var num,
str;
num = parseFloat(userInput); // e.g. 0.03
str = userInput.toString();
if (!isNaN(num) && str.substring(0, 1) === '0') {
str = str.substring(1); // e.g. .03
} else if (isNaN(num)) {
str = userInput; // it’s not a number, so just return the input
}
return str;
}
makePretty('000.03'); // '.03'
makePretty('020.03'); // '20.03'
It you feed it something it cannot parse as a number, it will just return it back.
Update: Oh, I see If the single leading zero needs to be removed as well. Updated the code.
Assuming your input's all the same format, and you want to display the .
user = "000.03";
user = user.substring(3);
You can convert a string into a number and back into a string to format it as "0.03":
var input = "000.03";
var output = (+input).toString(); // "0.03"
To get rid of any leading zeroes (e.g. ".03"), you can do:
var input = "000.03";
var output = input.substr(input.indexOf(".")); // ".03"
However, this improperly strips "20.30" to ".30". You can combine the first two methods to get around this:
var input = "000.03";
var output = Math.abs(+input) < 1 ?
input.substr(input.indexOf(".")) :
(+"000.03").toString();
As you know, the javascript's parseFloat function works only until it meets an invalid character, so for example
parseFloat("10.123") = 10.123
parseFloat("12=zzzz") = 12
parseFloat("z12") = NaN
Is there a way or an implementation of parseFloat that would return NaN if the whole string is not a valid float number?
Use this instead:
var num = Number(value);
Then you can do:
if (isNaN(num)) {
// take proper action
}
Maybe try:
var f = parseFloat( someStr );
if( f.toString() != someStr ) {
// string has other stuff besides the number
}
Update: Don't do this, use #dcp's method :)
var asFloat = parseFloat("12aa");
if (String(asFloat).length != "12aa".length) {
// The value is not completely a float
}
else {
// The value is a float
}