feat: is equal

src/utils/is.ts

@@ -1,4 +1,77 @@
+type Primitive = string | number | boolean | null | undefined
+
+const equal = {
+  type: (a: unknown, b: unknown) => getType(a) === getType(b),
+  unknown(a: unknown, b: unknown) {
+    const type = getType(a)
+    if (!equal.primitive(type, getType(b))) return false
+    switch (type) {
+      case 'array':
+        if (!equal.array(a as unknown[], b as unknown[])) return false
+        break
+      case 'object':
+        if (!equal.object(a as Record<string, unknown>, b as Record<string, unknown>)) return false
+        break
+      case 'date':
+      case 'function':
+      case 'regexp':
+      case 'symbol':
+        if (!equal.primitive(`${a}`, `${b}`)) return false
+        break
+      default:
+        if (!equal.primitive(a as Primitive, b as Primitive)) return false
+    }
+    return true
+  },
+  primitive: <T extends Primitive>(a: T, b: T) => a === b,
+  array(a: unknown[], b: unknown[]) {
+    if (a.length !== b.length) return false
+    const length = a.length
+    for (let i = 0; i < length; i++) if (!equal.unknown(a[i], b[i])) return false
+    return true
+  },
+  object(a: Record<string, unknown>, b: Record<string, unknown>) {
+    if (Object.keys(a).length !== Object.keys(b).length) return false
+  },
+}
+
+const shallowEqual = {
+  array(a: unknown[], b: unknown[]) {
+    if (a.length !== b.length) return false
+    const length = a.length
+    for (let i = 0; i < length; i++) if (a[i] !== b[i]) return false
+    return true
+  },
+}
+
+function getType(a: unknown) {
+  switch (typeof a) {
+    case 'boolean':
+      return 'boolean'
+    case 'function':
+      return 'function'
+    case 'number':
+      return 'number'
+    case 'string':
+      return 'string'
+    case 'symbol':
+      return 'symbol'
+    case 'undefined':
+      return 'undefined'
+    case 'object':
+      if (a === null) return 'null'
+      if (Array.isArray(a)) return 'array'
+      if (a instanceof Date) return 'date'
+      if (a instanceof RegExp) return 'regexp'
+      return 'object'
+    default:
+      return 'unknown'
+  }
+}
+
 export const is = {
+  equal,
+  shallowEqual,
   boolean: (d: unknown): d is boolean => typeof d === 'boolean',
   number: (d: unknown): d is number => typeof d === 'number',
   string: (d: unknown): d is string => typeof d === 'string',