api.error.md

Error Module

@mcaskill/html-build-attributes/error.js

The error module provides a custom Error object meant to be used by filter functions. This is mostly useful to catch errors related to attribute value filtering.

For all API functions listed:

• T represents any data type.
• AttrName is a string and represents an attribute name.
• AttrValue is a string or boolean and represents a filtered attribute value.

FilterError()

The FilterError object represents an error with a value being filtered.

Syntax

new FilterError(message: string, options?: object)

FilterError.describeAttr()

A static method to format the attribute name or value.

This method is used by the static creator method to generate a descriptor for the placeholder token.

Syntax

FilterError.describeAttr(value?: T, name?: AttrName): string

Examples

FilterError.describeAttr(null);
// → 'null'

FilterError.describeAttr(undefined);
// → 'undefined'

FilterError.describeAttr(true);
// → 'boolean'

FilterError.describeAttr(42);
// → 'number'

FilterError.describeAttr([ 1, 2, 3 ]);
// → 'Array'

FilterError.describeAttr({});
// → 'Object'

FilterError.describeAttr(new Date());
// → 'Date'

FilterError.describeAttr('hello');
// → 'string'

FilterError.describeAttr('hello', 'class');
// → 'attribute [class]'

FilterError.create()

A static method to create a new error object with a message where {attr} is a placeholder that will be substituded with a name or value.

Syntax

FilterError.create(
  message: string,
  value: T,
  name?: AttrName,
  options?: object
): FilterError

Example

function filterNumber(value, name) {
  if (typeof value === 'number') {
    return value;
  }

  throw FilterError.create('{attr} is not a number', value, name);
}

filterNumber(true);
// → Uncaught FilterError: boolean is not a number