How to Represent Integer in TypeScript

1. Use the number Type to Represent Numbers in TypeScript
2. Use the bigint to Represent Very Large Numbers in TypeScript
3. Use the parseInt Built-In Function to Convert From String to Integer in TypeScript
4. Use the + Operator to Convert a String to Number in TypeScript

In TypeScript, there is no concept of integer data types like in other programming languages. Only a number type is used to represent floating-point numbers in general.

The bigint is the latest version of TypeScript, which represents big integers.

Use the number Type to Represent Numbers in TypeScript

The number type in TypeScript can hold both integer and floating-point data types.

It can also store numbers having different bases like binary, octal and hexadecimal.

// the count of something is in whole numbers
var countDogs : number = 10;
// the price of a bag can be a floating point number
var priceBag : number = 200.99;
var binaryNumber : number = 0b101;
var octalNumber : number = 0o30;
var hexadecimalNumber : number = 0xFF;

console.log(countDogs);
console.log(priceBag);
console.log(binaryNumber);
console.log(octalNumber);
console.log(hexadecimalNumber);

Output:

10
200.99
5
24
255

The numbers in different bases are printed out in base 10. The binary or base 2 can be represented by prefixing with 0b or 0B, similarly for base 16, it has to be prefixed with 0x or 0X.

Use the bigint to Represent Very Large Numbers in TypeScript

The bigint type is used for representing very large numbers (numbers more than 2<sup>53</sup> - 1) and has the n character at the end of the integer literal.

var bigNumber: bigint = 82937289372323n;
console.log(bigNumber);

Output:

82937289372323 

Use the parseInt Built-In Function to Convert From String to Integer in TypeScript

The parseInt function is used for conversion from string to integer, and the parseFloat function is used to convert from string to floating-point data type.

var intString : string = "34";
var floatString : string = "34.56";

console.log(parseInt(intString));
console.log(parseInt(floatString));
console.log(parseFloat(intString));
console.log(parseFloat(floatString));

var notANumber : string = "string";
console.log(parseInt(notANumber));

Output:

34 
34 
34 
34.56 
NaN 

Thus the parseInt and parseFloat methods will return NaN.

Use the + Operator to Convert a String to Number in TypeScript

The + operator can convert a string literal to a number type. Further operations are done once it is converted to a number type.

function checkiFInt( val : number | string ) {
    if (( val as any) instanceof String){
        val = +val as number;
    }
    console.log(Math.ceil(val as number) == Math.floor(val as number));
}

checkiFInt('34.5');
checkiFInt('34');
checkiFInt('34.5232');
checkiFInt('34.9');
checkiFInt('0');

Output:

false
true
false
false
true