How can i get an array of the arguments of a constructor class in JS? It's possible? Thanks in advance.
class Product {
constructor(id, name, price, category, stock){
this.id = id;
this.name = name;
this.price = price;
this.category = category;
this.stock = stock;
}
};
console.log(Product.constructor.params);
//expected output = ['id', 'name', 'price', 'category', 'stock'];
let s = Product.toString();
let params = s.substring(s.indexOf('(')+1, s.indexOf(')')).split(',')
Inspired form @Porter answer and @evolutionxbox, I think that a reliable way would be using .match() like this:
class Product {
constructor(id, name, price, category, stock, unusedArgument) {
this.id = id;
this.name = name;
this.price = price;
this.category = category;
this.stock = stock;
}
}
class Noarguments {
constructor() {
}
}
// A function
function getClassContructorParams(obj){
let match = obj.toString().match(/constructor\((.+)\)/)
if(match && match[1]){
return match[1].split(",");
}
// If no match
return []
}
console.log(getClassContructorParams(Product))
/// Testing a class with no constructor arguments will return an empty array
console.log(getClassContructorParams(Noarguments))My previous answer was returning the object properties, which may be different from the arguments used in the constructor...
Now using .match() will ensure what is returned really are the constructor arguments.
Object.keys(new Product) produces the same result.
My point in the comments was it seems you're coming at this problem from the wrong direction. Maybe take this approach. Have an array of labels, and array of data, and pass those into the class. You'll still have the array of labels to access (and validate) in your other code, and everything will still work.
const labels = [ 'id', 'name', 'price', 'category', 'stock' ];
const data = [ 1, 'Bob', 100, 2, 1];
class Product {
constructor(labels, data) {
data.forEach((el, i) => this[labels[i]] = el);
}
};
console.log(new Product(labels, data));
console.log(labels);Or, if your products are identical in terms of properties you could just use an array of them, and use Object.keys to get the labels of the first object.
const data = [{ id: 1, name: 'Bob', price: 100, category: 2, stock: 1 }];
const labels = Object.keys(data[0]);
class Product {
constructor(data) {
for (let key in data) {
this[key] = data[key];
}
}
};
console.log(new Product(data[0]));
console.log(labels);There are some things to take into account:
Look at the snippet(code) and read the comment lines; I tried to explain clearly each line of code.
class c1 {
//the worst and ugliest code scenario
constructor(id
, innerHTML , classes = "") {
this.id=id
this.innerHTML=innerHTML
this.class=classes
}
}
function getClassConstructorParameters(cr) {//class reference
//get the params; it takes into account blanks spaces and line breaks
let params = cr.toString().match(/\(([^\)]+)/)
//remove all line breaks and blank spaces
params = params[1].replace(/[\r\n\s]+/gm, "");
//split the params
params = params.split(',')
//remove default values
params = params.map((value, index, array) => {
return value.split('=')[0];
})
return params
}
console.log(getClassConstructorParameters(c1))
