Online Javascript to Typescript Converter Tool

Online Javascript to Typescript Converter

This is a utility tool to convert a JavaScript codebase to TypeScript, while trying to solve some of the common TypeScript errors that will be received upon such a conversion.

Javascript to Typescript Converter

Input (Editable)



Basic variable types

Type Example Notes
number let myNumber: number = 6 Represent all numbers : integer, float, hex etc.
string let fullName: string = Bob Bobbington Text with all text functions (indexOf, replace etc.)
boolean let isTrue: boolean = true true/false value
Array let list: Array = [1, 2, 3] Shorter version: let list: number[] = [1, 2, 3];
Tuple let x: [string, number] = ['test', 2]; Array contains ains items with various types
any let x: any = 2; Everything can be assigned to value with any type
Enum enum Color {Red, Blue } Usage: let c: Color = Color.Blue;
Never function fail(): never {while(true) {}} Indicating that something never should happen
Null or undefined let u: undefined = undefined; In TS there is dedicated type for null and undefined
Object let x:Object = {id: 2}; Represents any object
Function let myFn:Function = function() {...} Represents any function


Concept Code
Function { (arg1 :Type, argN :Type) :Type; } or (arg1 :Type, argN :Type) => Type;
Constructor { new () :ConstructedType; } or new () => ConstructedType;
Function type with optional param (arg1 :Type, optional? :Type) => ReturnType;
Function type with rest param (arg1 :Type, ...allOtherArgs :Type[]) => ReturnType;
Function type with static property { () :Type; staticProp :Type; }
Default argument function fn(arg1 :Type = 'default') :ReturnType {}
Arrow function (arg1 :Type) :ReturnType =>; {} or (arg1 :Type) :ReturnType =>; Expression

rimitive Types

Type Code
Any type (explicitly untyped) any
void type (null or undefined, use for function returns only) void
String string
Number number
Boolean boolean

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