Refactor code-style

*   Add more docs to JSDoc
*   Add support for `null`, `undefined` in input of API types

Author: wooorm

lib/index.js

@@ -4,67 +4,60 @@
  * @typedef {[number, number]} RangeLike
  *
  * @typedef PointLike
- * @property {number|null|undefined} [line]
- * @property {number|null|undefined} [column]
+ * @property {number | null | undefined} [line]
+ * @property {number | null | undefined} [column]
  *
  * @typedef LocLike
- * @property {PointLike|null|undefined} [start]
- * @property {PointLike|null|undefined} [end]
+ * @property {PointLike | null | undefined} [start]
+ * @property {PointLike | null | undefined} [end]
  *
  * @typedef NodeLike
- * @property {LocLike|null|undefined} [loc]
- * @property {RangeLike|null|undefined} [range]
- * @property {number|null|undefined} [start]
- * @property {number|null|undefined} [end]
+ * @property {LocLike | null | undefined} [loc]
+ * @property {RangeLike | null | undefined} [range]
+ * @property {number | null | undefined} [start]
+ * @property {number | null | undefined} [end]
  */
 
 /**
- * Given an estree `node`, returns a unist `position`.
- * @param {NodeLike|null} [value]
+ * Turn an estree `node` into a unist `position`.
+ *
+ * @param {NodeLike | null | undefined} [value]
+ *   estree node.
  * @returns {Position}
+ *   unist position.
  */
 export function positionFromEstree(value) {
-  /** @type {NodeLike} */
   const node = value || {}
-  /** @type {LocLike} */
   const loc = node.loc || {}
-  /** @type {RangeLike} */
   const range = node.range || [0, 0]
-  const startOffset = range[0] || node.start
-  const endOffset = range[1] || node.end
+  const startColumn = loc.start
+    ? numberOrUndefined(loc.start.column)
+    : undefined
+  const endColumn = loc.end ? numberOrUndefined(loc.end.column) : undefined
 
   return {
     start: {
       // @ts-expect-error: return no point / no position next major.
-      line:
-        loc.start && typeof loc.start.line === 'number' && loc.start.line > -1
-          ? loc.start.line
-          : undefined,
+      line: loc.start ? numberOrUndefined(loc.start.line) : undefined,
       // @ts-expect-error: return no point / no position next major.
-      column:
-        loc.start &&
-        typeof loc.start.column === 'number' &&
-        loc.start.column > -1
-          ? loc.start.column + 1
-          : undefined,
-      offset:
-        typeof startOffset === 'number' && startOffset > -1
-          ? startOffset
-          : undefined
+      column: startColumn === undefined ? undefined : startColumn + 1,
+      offset: numberOrUndefined(range[0] || node.start)
     },
     end: {
       // @ts-expect-error: return no point / no position next major.
-      line:
-        loc.end && typeof loc.end.line === 'number' && loc.end.line > -1
-          ? loc.end.line
-          : undefined,
+      line: loc.end ? numberOrUndefined(loc.end.line) : undefined,
       // @ts-expect-error: return no point / no position next major.
-      column:
-        loc.end && typeof loc.end.column === 'number' && loc.end.column > -1
-          ? loc.end.column + 1
-          : undefined,
-      offset:
-        typeof endOffset === 'number' && endOffset > -1 ? endOffset : undefined
+      column: endColumn === undefined ? undefined : endColumn + 1,
+      offset: numberOrUndefined(range[1] || node.end)
     }
   }
 }
+
+/**
+ *
+ * @param {number | null | undefined} value
+ * @returns {number | undefined}
+ */
+function numberOrUndefined(value) {
+  return typeof value === 'number' && value > -1 ? value : undefined
+}