@meltwater/coerce

A simple javascript package for type checking an object

Install

npm i --save @meltwater/coerce

Usage

class ValidatedObject {
    constructor({ value }) {
        if(typeof value !== string) {
            throw new TypeError(`options.value must be a string. Provided value: ${value}`);
        }

        this.value = value;
        Object.freeze(this);
    }
}

const badValue = { value: 1234 };
coerce(badValue, ValidatedObject, 'Booooooom!');
// This will throw a TypeError with the message 'Booooooom!'

const goodValue = { value: 'so good' };
const typedValue = coerce(goodValue, ValidatedObject, 'Booooooom');
// This will return a new object that is an instanceof ValidatedObject with typedValue.value === 'so good'

API reference

Table of Contents

• coerce
  • Parameters
• coerceArray
  • Parameters

coerce

If value is an instance of Type, this function returns it. Otherwise this function attempts to construct a new instance Type using value as a constructor parameter.

Parameters

• value any The value to coerce
• Type any The type to return the object as.
• message string The error message if coercion fails

• Throws TypeError If the value is not coercable.

Returns any Instance of provided Type

coerceArray

Apply coerce to an array for a single type.

Parameters

• values Array<any> The array of values to coerce
• Type any The type each object should be
• message string The error message if coercion fails

• Throws TypeError If values is not an array
• Throws TypeError One of the array values is not coercable.

Returns Array<any> Array of instances of provided Type