I was trying to do a "multiple filter" in TS, So…

If i send nothing -> it returns all products normally;

But if i send some params -> it returns products filtered by the params.

(I used colors just for the example)

async load(params: params): LoadProducts.Result => {
  const products = [];

  if (params) {
    if (params.red != undefined) // products.push( ...load.redProducts() );
    if (params.blue != undefined) // products.push( ...load.blueProducts() );
    if (params.green != undefined) // products.push( ...load.greenProducts() );
    if (params.yellow != undefined) // products.push( ...load.yellowProducts() );
  } else {
    // products.push( ...load.products() );
  }

  return products;
}

Type of request:

type params = {
  filter?: {
    red?:  boolean;
    blue?: boolean;
    green?: boolean;
    yellow?: boolean;
  };
};

Example of request:

{
  "filter": {
    "red": true,
    "blue": true
  }
}

How can I deal with the multiple IFs to verify the params, because each has its own function to load and I want to add more filters.

>Solution :

You have not included a minimal, reproducible example, but based on what you have shown, you can use a (map-like) array of tuples and iterate over it:

const colorFns = [
  ['red', load.redProducts.bind(load)],
  ['blue', load.blueProducts.bind(load)],
  // etc...
] as const;

async load(params: params): LoadProducts.Result => {
  const products = [];

  if (params) {
    for (const [color, fn] of colorFns) {
      if (params[color] != undefined) products.push(...fn());
    }
  } else {
    // products.push( ...load.products() );
  }

  return products;
}