New model update details, author and series inputs with create new, compare & copy utils

server/utils/areEquivalent.js

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+/**
+ * https://gist.github.com/DLiblik/96801665f9b6c935f12c1071d37eae95
+ Compares two items (values or references) for nested equivalency, meaning that
+ at root and at each key or index they are equivalent as follows:
+ - If a value type, values are either hard equal (===) or are both NaN
+     (different than JS where NaN !== NaN)
+ - If functions, they are the same function instance or have the same value
+     when converted to string via `toString()`
+ - If Date objects, both have the same getTime() or are both NaN (invalid)
+ - If arrays, both are same length, and all contained values areEquivalent
+     recursively - only contents by numeric key are checked
+ - If other object types, enumerable keys are the same (the keys themselves)
+     and values at every key areEquivalent recursively
+ Author: Dathan Liblik
+ License: Free to use anywhere by anyone, as-is, no guarantees of any kind.
+ @param value1 First item to compare
+ @param value2 Other item to compare
+ @param stack Used internally to track circular refs - don't set it
+ */
+module.exports = function areEquivalent(value1, value2, stack = []) {
+  // Numbers, strings, null, undefined, symbols, functions, booleans.
+  // Also: objects (incl. arrays) that are actually the same instance
+  if (value1 === value2) {
+    // Fast and done
+    return true;
+  }
+
+  const type1 = typeof value1;
+
+  // Ensure types match
+  if (type1 !== typeof value2) {
+    return false;
+  }
+
+  // Special case for number: check for NaN on both sides
+  // (only way they can still be equivalent but not equal)
+  if (type1 === 'number') {
+    // Failed initial equals test, but could still both be NaN
+    return (isNaN(value1) && isNaN(value2));
+  }
+
+  // Special case for function: check for toString() equivalence
+  if (type1 === 'function') {
+    // Failed initial equals test, but could still have equivalent
+    // implementations - note, will match on functions that have same name
+    // and are native code: `function abc() { [native code] }`
+    return value1.toString() === value2.toString();
+  }
+
+  // For these types, cannot still be equal at this point, so fast-fail
+  if (type1 === 'bigint' || type1 === 'boolean' ||
+    type1 === 'function' || type1 === 'string' ||
+    type1 === 'symbol') {
+    return false;
+  }
+
+  // For dates, cast to number and ensure equal or both NaN (note, if same
+  // exact instance then we're not here - that was checked above)
+  if (value1 instanceof Date) {
+    if (!(value2 instanceof Date)) {
+      return false;
+    }
+    // Convert to number to compare
+    const asNum1 = +value1, asNum2 = +value2;
+    // Check if both invalid (NaN) or are same value
+    return asNum1 === asNum2 || (isNaN(asNum1) && isNaN(asNum2));
+  }
+
+  // At this point, it's a reference type and could be circular, so
+  // make sure we haven't been here before... note we only need to track value1
+  // since value1 being un-circular means value2 will either be equal (and not
+  // circular too) or unequal whether circular or not.
+  if (stack.includes(value1)) {
+    throw new Error(`areEquivalent value1 is circular`);
+  }
+
+  // breadcrumb
+  stack.push(value1);
+
+  // Handle arrays
+  if (Array.isArray(value1)) {
+    if (!Array.isArray(value2)) {
+      return false;
+    }
+
+    const length = value1.length;
+
+    if (length !== value2.length) {
+      return false;
+    }
+
+    for (let i = 0; i < length; i++) {
+      if (!areEquivalent(value1[i], value2[i], stack)) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  // Final case: object
+
+  // get both key lists and check length
+  const keys1 = Object.keys(value1);
+  const keys2 = Object.keys(value2);
+  const numKeys = keys1.length;
+
+  if (keys2.length !== numKeys) {
+    return false;
+  }
+
+  // Empty object on both sides?
+  if (numKeys === 0) {
+    return true;
+  }
+
+  // sort is a native call so it's very fast - much faster than comparing the
+  // values at each key if it can be avoided, so do the sort and then
+  // ensure every key matches at every index
+  keys1.sort();
+  keys2.sort();
+
+  // Ensure perfect match across all keys
+  for (let i = 0; i < numKeys; i++) {
+    if (keys1[i] !== keys2[i]) {
+      return false;
+    }
+  }
+
+  // Ensure perfect match across all values
+  for (let i = 0; i < numKeys; i++) {
+    if (!areEquivalent(value1[keys1[i]], value2[keys1[i]], stack)) {
+      return false;
+    }
+  }
+
+  // back up
+  stack.pop();
+
+  // Walk the same, talk the same - matching ducks. Quack.
+  // 🦆🦆
+  return true;
+}