To check if a variable (including a string) is a number, check if it is not a number: This works regardless of whether the variable content is a string or number. isNaN(num) // returns true if the variable does NOT contain a valid number Examples isNaN(123) // false isNaN('123'...
// If the new String method startsWith() is not already defined... if (!String.prototype.startsWith) { // ...then define it like this using the older indexOf() method. String.prototype.startsWith = function(s) { return this.indexOf(s) === 0; }; } 这里是另一个例子: 代码语言:...
Also, just to check whether the substring is present in the string or not then we can apply a condition. If the index of the sub-string is not equals to (-1) then obviously it is present in the given string and hence it will return true, if not then it will retur...
str3 = new String('Great Place'); Now to check whether a given variable is a string or not, we'll use a JavaScript operator calledtypeof. Syntax: typeof variable; This operator returns the data type of the variable specified after it. If the variable is of string data type, it will...
Step 1: We have to find out if the given string is a palindrome or not. So to do this task we will create a function called isPalindrome and in this function, we will pass a parameter of string as str. So for this str, we will check the palindrome condition. Step 2: After the...
{ minimum: 10, maximum: 20 };// Bind the checkNumericRange function.var boundCheckNumericRange = checkNumericRange.bind(range);// Use the new function to check whether 12 is in the numeric range.var result = boundCheckNumericRange (12);document.write(result);// Output: true // Define ...
It can be used to determine if a variable is a number, string, boolean, function, or object. Array.isArray() is a method that determines whether the passed value is an Array. How to Use typeof and Array.isArray(): Using typeof: Syntax: typeof variable. Example: let myVar = '...
isSafeInteger() Determines whether the passed value is a safe integer. parseFloat() Converts the numeric floating string to a floating-point number. parseInt() Converts the numeric string to an integer. toExponential() Returns a string value for a number in exponential notation. toFixed() Retu...
Concatenate two string in asp:label text property Conditional validation using required field validator Configuration element is not declared Confirm Message Box with OK or Cancel option in C# confirmation alert box in c# on condition check Content controls have to be top-level controls in a content...
NullLiteral, BooleanLiteral, NumberLiteral, StringLiteral, RegExpLiteral: different kinds of literals. ThisExpr: a “this” expression. SuperExpr: a “super” expression. ArrayExpr: an array expression; use ArrayExpr.getElement(i) to obtain the ith element expression, and ArrayExpr.elementIsOmitt...