Scenario

We have PurchaseOrderDTO decorated with Firefly Semantics Validator decorators.

The instances are coming in over the wire as described here.

We wish to construct PurchaseOrder instances using the PurchaseOrderDTO instances and then validate the following:

• The quantity is an integer
• Both the purchaseDate and the receiptDate are Date instances.
• The…

Updated Version

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Scenario

We are receiving data transfer object instances with a PurchaseOrderDTO type and we need to validate them using Firefly Semantics Validator:

Approach

The PurchaseOrderDTO has been annotated with Firefly Semantics Validator validation annotations as follows:

We will create an instance an validate…

Scenario

For our prototyping work we want a Typescript starter project preconfigured with Jest, Typedoc, and NPM Workflow Scripts.

Cloning it like this creates the project <project_name>:

git clone git@github.com:fireflysemantics/typescript-starter.git <project_name>

This is the final repository in case you want to get right to it:

Approach

First create a new Node project:

…

Updated Article Version

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Scenario

We have an array of elements [1,2,'a'] , and we want to see whether all of the elements in the array are numbers.

Approach

This approach uses:

@fireflysemantics/validatorts to check whether the array element is a number:

let arr: any[] = [1, 2, 'a'];function allNumbersPredicate(v: any, index: number, array: any[]):boolean {
   console.log(`is number ${isNumber(v).value}`);
   return isNumber(v).value;
}
console.log(`All numbers:? ${arr.every(allNumbers)}`);

Demo

Scenario

We have a RANGE_DEFAULT_OPTIONS object:

const RANGE_DEFAULT_OPTIONS = { min: 0, max: 100 }

And we want to use the defaults, unless the API overrides them:

export function range(value:number, options:any) {
   ...
}

Approach

options = { ...RANGE_DEFAULT_OPTIONS, ...options }

Demo

Scenario

We have an array [1,2,3] and we want to know whether the numbers are unique.

Approach

function isArrayUnique(target: any[]): boolean {
const uniqueItems = target.filter((a, b, c) => c.indexOf(a) === b);
   return target.length === uniqueItems.length;
}

Demo

Scenario

We have a simple function contains that tests whether a string contains another:

/**
 * Test whether the target string contains the contained string.
 *
 * @param target The string that should contains the element
 * @param contained The possibly contained string
 * @return true if the `target` string contains…