Calling function from HTML to typescript not waited to finish

I have an HTML element as bellow

<div *ngFor="let item of items">
    <input type='number' [min]="getMinData(param1,param2)" />
</div>

inside ts file

 getMinData(rules: ConstraintRule[], id: string) {
    rules.forEach((rule) => {
      rule._metadata.productList.forEach((product: SProduct) => {
        product.OptionGroups.forEach((optionGroup: SProductOptionGroup) => {
          optionGroup.Options.forEach((option: SProductOptionComponent) => {
            if (option.ComponentProductId == id) {
              return option.MinQuantity;
            }
          });
        });
      });
    });
  }

Also, there's no any API call or any other thing, it's just filtration over the local data.

But, On HTML correct qty is not returned.

You have to return something for getMinData function.

Currently, you call return option.MinQuantity;, but it is result for an anonymous function - (option: SProductOptionComponent) => {.

If you just want to find the first option.MinQuantity, try this function:

getMinData(rules: ConstraintRule[], id: string) {
  let minQuantity = 0;

  rules.forEach((rule) => {
    rule._metadata.productList.forEach(({ OptionGroups }) => {
      OptionGroups.forEach(({ Options }) => {
        const foundOption = Options.find((o) => o.ComponentProductId === id);
        minQuantity = foundOption ? foundOption.MinQuantity : 0; // Default min value is 0
      });
    });
  });

  return minQuantity; // return value
}