Merge pull request #33 from takayukister/dev/1.4

Introduce stepnumber rule type

rules/README.md

@@ -116,6 +116,13 @@ A `minfilesize` rule verifies that the size of the file object value of the fiel
 A `maxfilesize` rule verifies that the size of the file object value of the field specified by the `field` property is not larger than the size specified by the `threshold` property.
 
 
+## stepnumber
+
+A `stepnumber` rule verifies that the field specified by the `field` property is empty or has a numerical value that matches one of the allowed values calculated based on the `base` and `interval` properties. Specifically, when the field value is equal to the base value plus an integral multiple of the interval value, the rule is validated.
+
+Both the `base` and `interval` properties must have an integer or a floating-point number value. The use of an `any` keyword, which HTML supports as the `step` attribute value, is not supported.
+
+
 ## all
 
 An `all` rule verifies that all of the child rules in the `rules` property are verified. Child rules are evaluated in order from the top, and if one of the rules fails, the iteration will terminate there.
@@ -174,6 +181,7 @@ This is the meta schema for SWV schemas based on [JSON Schema](https://json-sche
                             "maxdate",
                             "minfilesize",
                             "maxfilesize",
+                            "stepnumber",
                             "all",
                             "any"
                         ]
@@ -191,6 +199,13 @@ This is the meta schema for SWV schemas based on [JSON Schema](https://json-sche
                             "type": "string"
                         }
                     },
+                    "base": {
+                        "type": "string"
+                    },
+                    "interval": {
+                        "type": "number",
+                        "minimum": 0
+                    },
                     "threshold": {
                         "type": "string"
                     }

rules/index.js

@@ -19,5 +19,6 @@ export { mindate } from './mindate';
 export { maxdate } from './maxdate';
 export { minfilesize } from './minfilesize';
 export { maxfilesize } from './maxfilesize';
+export { stepnumber } from './stepnumber';
 export { all } from './all';
 export { any } from './any';

rules/stepnumber.js

@@ -0,0 +1,31 @@
+import { ValidationError } from '../error';
+
+export const stepnumber = function ( formDataTree ) {
+	const values = formDataTree.getAll( this.field );
+
+	const base = parseFloat( this.base );
+	const interval = parseFloat( this.interval );
+
+	if ( ! ( 0 < interval ) ) {
+		return true;
+	}
+
+	const matchesStep = text => {
+		text = text.trim();
+
+		const remainder = ( parseFloat( text ) - base ) % interval;
+
+		if (
+			'0.000000' === Math.abs( remainder ).toFixed( 6 ) ||
+			'0.000000' === Math.abs( remainder - interval ).toFixed( 6 )
+		) {
+			return true;
+		}
+
+		return false;
+	};
+
+	if ( ! values.every( matchesStep ) ) {
+		throw new ValidationError( this );
+	}
+};