javascript check if number
function isNumber(n) { return /^-?[\d.]+(?:e-?\d+)?$/.test(n); }
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isNumber('123'); // true
isNumber('123abc'); // false
isNumber(5); // true
isNumber('q345'); // false
isNumber(null); // false
isNumber(undefined); // false
isNumber(false); // false
isNumber(' '); // falsejavascript check if variable is number
function isNumber(n) {
return !isNaN(parseFloat(n)) && !isNaN(n - 0);
}check data type in js
typeof("string"); //string
typeof(123); //numbertype of javascript
//typeof() will return the type of value in its parameters.
//some examples of types: undefined, NaN, number, string, object, array
//example of a practical usage
if (typeof(value) !== "undefined") {//also, make sure that the type name is a string
//execute code
}js typeof number
console.log(typeof 93);
// Output = "number"
console.log(typeof 'Maximum');
// Output = 'string'
console.log(typeof false);
// Output = "boolean"
console.log(typeof anUndeclaredVariable);
// Output = "undefined"Copyright © 2021 Codeinu
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