Typescript namespace

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1. What is a namespace ?

 A namespace can be seen as a tiny module ,
 When we first write the relevant business code together ,  When you don't want to pollute the global space ,  We can use namespaces 
 The essence is to define a large object ,  Put variables / Method / class / Interface ... Put everything in it 

2. Namespace is different from module

 Code used inside the program ,  You can use namespaces to encapsulate and prevent global pollution 
 Code used inside and outside the program ,  Modules can be used to encapsulate and prevent global contamination 
 summary :  Because the module can also realize the same function ,  So in most cases, you can use modules 

namespace Validation {
    
    const lettersRegexp = /^[A-Za-z]+$/;
    export const LettersValidator  = (value) =>{
    
        return lettersRegexp.test(value);
    }
}
console.log(Validation.LettersValidator('abc'));
console.log(Validation.LettersValidator(123));

Methods that call namespaces from other locations
./56/test.ts

namespace Validation {
    
    const lettersRegexp = /^[A-Za-z]+$/;
    export const LettersValidator  = (value) =>{
    
        return lettersRegexp.test(value);
    }
}

/// <reference path="./56/test.ts" />
console.log(Validation.LettersValidator('abc'));
console.log(Validation.LettersValidator(123));