Mastering TypeScript 3 - Third Edition

Finding parameter types

Now that we know what each of our constructor parameter names are, we need to match these with a parameter type. In order to do this, we will need to make use of the reflect-metadata package in our ConstructorInject decorator, as follows:

let parameterTypeArray =  
    Reflect.getMetadata("design:paramtypes", classDefinition); 
console.log(`parameterTypeArray:`); 
console.log(`===================`); 
console.log(`${parameterTypeArray}`); 
console.log(`===================`); 
 
for (let type of parameterTypeArray) { 
    console.log(`found type : ${type.name}`); 
} 

Here, we are calling the Reflect.getMetadata function, and using the "design:paramtypes" argument to extract an array from the class definition. We then print this array to ...