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Number, Eval Methods in Javascript, Learn JavaScript Syntax

In JavaScript there is only one type for all numbers, all numbers are treated as floating-point numbers. though the dot is not displayed if there is no digit after the decimal point.

Converting to Number

JavaScript has in-built Number() Function
Let's take a look at some example how to convert different object values to numbers using Number() Function in JavaScript
var a1 = new Date();
var a2 = true;
var a3 = false;
var a4 = 99.99;
var a5 = "999";
var a6 = "999 888";
document.writeln(Number(a6)); </script>
After executing the above code here is the result

Use of eval() function in JavaScript
Now think of a situation where you receive user input as number and do some calculation based on that. Suppose you receive a number as string, but you need to perform some calculation, in such scenario you have to use eval() function.
eval() is used for evaluating the expression
var n1 = 10;
var n2 = 5;
var stringFormat = n1 + " + " + n2;
document.writeln(stringFormat); // 10 + 5
// using eval method
document.writeln(eval(stringFormat)); // 15

Number to String in JavaScript
            var x = 721;  
x.toString();            // returns 721 from variable x
(123).toString();        // returns 721 from literal 123 
(700 + 21).toString();   // returns 721 from expression 700 + 21

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Number, Eval Methods in Javascript, Learn JavaScript Syntax

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