Answer by funnyfish for Why does isNaN("") (string with spaces) equal false?
I use the following.x=(isNaN(parseFloat(x)))? 0.00 : parseFloat(x);
View ArticleAnswer by Aamir Mahmood for Why does isNaN("") (string with spaces) equal false?
let isNotNumber = val => isNaN(val) || (val.trim && val.trim() ===...
View ArticleAnswer by justin for Why does isNaN("") (string with spaces) equal false?
I find it convenient to have a method specific to the Number class (since other functions that do conversions like parseInt have different outputs for some of these values) and use prototypal...
View ArticleAnswer by Channox for Why does isNaN("") (string with spaces) equal false?
When checking if certain string value with whitespace or ""is isNaN maybe try to perform string validation, example :// value = "123 "if (value.match(/\s/) || isNaN(value)) { // do something}
View ArticleAnswer by Shuai Li for Why does isNaN("") (string with spaces) equal false?
NaN !== "not a number"NaN is a value of Number Typethis is a definition of isNaN() in ECMAScript1. Let num be ToNumber(number).2. ReturnIfAbrupt(num).3. If num is NaN, return true.4. Otherwise, return...
View ArticleAnswer by kiranvj for Why does isNaN("") (string with spaces) equal false?
I use this function isNotANumeric(val) {if(val.trim && val.trim() == "") { return true; } else { return isNaN(parseFloat(val * 1)); } } alert(isNotANumeric("100")); // false...
View ArticleAnswer by Nadav for Why does isNaN("") (string with spaces) equal false?
As other explained the isNaN function will coerce the empty string into a number before validating it, thus changing an empty string into 0 (which is a valid number).However, I found that the parseInt...
View ArticleAnswer by Om Sao for Why does isNaN("") (string with spaces) equal false?
isNAN(<argument>) is a function to tell whether given argument is illegal number.isNaN typecasts the arguments into Number type. If you want to check if argument is Numeric or not? Please use...
View ArticleAnswer by Bekim Bacaj for Why does isNaN("") (string with spaces) equal false?
The JavaScript built-in isNaN function, is - as should be expected by default - a "Dynamic Type Operator".Therefore all values which (during the DTC process) may yield a simple true | false such as "",...
View ArticleAnswer by James Donnelly for Why does isNaN("") (string with spaces) equal...
The Not-Entirely-Correct AnswerAntonio Haley's highly upvoted and accepted answer here makes a wrong assumption that this process goes through JavaScript's parseInt function:You can use parseInt on the...
View ArticleAnswer by XtraSimplicity for Why does isNaN("") (string with spaces) equal...
I wrote this quick little function to help solve this problem.function isNumber(val) { return (val != undefined && val != null && val.toString().length > 0 &&...
View ArticleAnswer by JacquesB for Why does isNaN("") (string with spaces) equal false?
The isNaN function expects a Number as its argument, so arguments of any other type (in your case a string) will be converted to Number before the actual function logic is performed. (Be aware that NaN...
View ArticleAnswer by dopeddude for Why does isNaN("") (string with spaces) equal false?
From MDN reason for the issue you are facingWhen the argument to the isNaN function is not of type Number, the value is first coerced to a Number. The resulting value is then tested to determine...
View ArticleAnswer by lucono for Why does isNaN("") (string with spaces) equal false?
That isNaN("") is false is part of the confusing behavior of the isNaN global function due to its coercion of non-numbers to a numeric type.From MDN:Since the very earliest versions of the isNaN...
View ArticleAnswer by Steven Pribilinskiy for Why does isNaN("") (string with spaces)...
The function isNaN("") performs a String to Number type coercionECMAScript 3-5 defines the following return values for the typeof operator:undefinedobject (null, objects,...
View ArticleAnswer by Alexander Schmidt for Why does isNaN("") (string with spaces) equal...
What about function isNumberRegex(value) { var pattern = /^[-+]?\d*\.?\d*$/i; var match = value.match(pattern); return value.length > 0 && match != null;}
View ArticleAnswer by bruno negrao for Why does isNaN("") (string with spaces) equal false?
This function seemed to work in my testsfunction isNumber(s) { if (s === "" || s === null) { return false; } else { var number = parseInt(s); if (number == 'NaN') { return false; } else { return true;...
View ArticleAnswer by Bat_Programmer for Why does isNaN("") (string with spaces) equal...
I suggest you to use the following function if you really want a proper check if it is an integer:function isInteger(s){ return Math.ceil(s) == Math.floor(s);}
View ArticleAnswer by Brian Grinstead for Why does isNaN("") (string with spaces) equal...
If you would like to implement an accurate isNumber function, here is one way to do it from Javascript: The Good Parts by Douglas Crockford [page 105]var isNumber = function isNumber(value) { return...
View ArticleAnswer by Nick Berardi for Why does isNaN("") (string with spaces) equal false?
You may find this surprising or maybe not, but here is some test code to show you the wackyness of the JavaScript engine.document.write(isNaN("")) // falsedocument.write(isNaN("")) //...
View ArticleAnswer by Rafael for Why does isNaN("") (string with spaces) equal false?
To understand it better, please open Ecma-Script spec pdf on page 43 "ToNumber Applied to the String Type"if a string has a numerical syntax, which can contain any number of white-space characters, it...
View ArticleAnswer by Joel Coehoorn for Why does isNaN("") (string with spaces) equal false?
I'm not sure why, but to get around the problem you could always trim whitespace before checking. You probably want to do that anyway.
View ArticleAnswer by Greg for Why does isNaN("") (string with spaces) equal false?
I think it's because of Javascript's typing: '' is converted to zero, whereas 'x' isn't:alert('' * 1); // 0alert('x' * 1); // NaN
View ArticleAnswer by bendewey for Why does isNaN("") (string with spaces) equal false?
Try using:alert(isNaN(parseInt("")));Oralert(isNaN(parseFloat("")));
View ArticleAnswer by Antonio Haley for Why does isNaN("") (string with spaces) equal false?
JavaScript interprets an empty string as a 0, which then fails the isNAN test. You can use parseInt on the string first which won't convert the empty string to 0. The result should then fail isNAN.
View ArticleWhy does isNaN("") (string with spaces) equal false?
In JavaScript, why does isNaN("") evaluate to false, but isNaN(" x") evaluate to true?I’m performing numerical operations on a text input field, and I’m checking if the field is null, "", or NaN. When...
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