javascript check if a numer code example

Example 1: 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('   '); // false

Example 2: check to see if number is a decimal javascript

The Number. isInteger() method determines whether a 
value an integer. 
This method returns true if the value is of the type 
Number, and an integer (a number without decimals). 
Otherwise it returns false.