@jsopen/objects/esm/merge.js

Helper utilities for working with JavaScript objects and arrays

import { isObject, isPlainObject } from './is-object.js';
import { isBuiltIn } from './type-guards.js';
export function merge(target, source, options) {
    if (!(isObject(target) || typeof target === 'function')) {
        throw new TypeError('"target" argument must be an object');
    }
    source = source || {};
    if (!(isObject(source) || typeof target === 'function')) {
        throw new TypeError('"target" argument must be an object');
    }
    const fn = getMergeFunction(options);
    return fn(target, source, options, '');
}
const functionCache = new Map();
export function getMergeFunction(options) {
    const cacheKey = [
        options?.deep,
        options?.moveArrays,
        options?.keepExisting,
        options?.copyDescriptors,
        options?.ignore,
        options?.ignoreUndefined,
        options?.ignoreNulls,
        options?.filter,
    ]
        .map(option => option == null
        ? 'n'
        : typeof option === 'function'
            ? 'f'
            : typeof option === 'string'
                ? option
                : option
                    ? '1'
                    : '0')
        .join();
    let fn = functionCache.get(cacheKey);
    if (!fn) {
        fn = buildMerge(options);
        functionCache.set(cacheKey, fn);
    }
    return fn;
}
function buildMerge(options) {
    const scriptL0 = [
        `
const { merge, isObject, isPlainObject, deepTest, arrayClone } = context;
const hasOwnProperty = Object.prototype.hasOwnProperty;
const keys = Object.getOwnPropertyNames(source);
keys.push(...Object.getOwnPropertySymbols(source));
let key;
let descriptor;
let srcVal;
let trgVal;
`,
    ];
    // noinspection JSUnusedGlobalSymbols
    const context = {
        deepTest: isPlainObject,
        isPlainObject,
        isObject,
        arrayClone,
        merge: null,
    };
    if (options?.deep) {
        if (options.deep === 'full') {
            context.deepTest = v => v && typeof v === 'object' && !isBuiltIn(v);
        }
        scriptL0.push(`let subPath;`, `let _isArray;`);
        if (typeof options?.deep === 'function') {
            scriptL0.push(`const deepCallback = options.deep;`);
        }
    }
    if (typeof options?.ignore === 'function') {
        scriptL0.push('const ignoreCallback = options.ignore;');
    }
    if (typeof options?.filter === 'function') {
        scriptL0.push('const filterCallback = options.filter;');
    }
    if (typeof options?.copyDescriptors === 'function') {
        scriptL0.push(`const copyDescriptorsCallback = options.copyDescriptors;`);
    }
    if (typeof options?.moveArrays === 'function') {
        scriptL0.push(`const moveArraysCallback = options.moveArrays;`);
    }
    scriptL0.push(`
if (isPlainObject(target)) Object.setPrototypeOf(target, Object.getPrototypeOf(source));  
let i = 0;
const len = keys.length;
for (i = 0; i < len; i++) {
  key = keys[i];
  /** Should not overwrite __proto__ and constructor properties */
  if (key === '__proto__' || key === 'constructor') continue;
`);
    const scriptL1For = [];
    scriptL0.push(scriptL1For);
    scriptL0.push('}');
    /** ************* filter *****************/
    if (options?.filter) {
        scriptL1For.push(`
if (!filterCallback(key, source, target, curPath)) {
  delete target[key];
  continue;
}`);
    }
    /** ************* ignore *****************/
    if (typeof options?.ignore === 'function') {
        scriptL1For.push(`
if (
      hasOwnProperty.call(target, key) && 
      ignoreCallback(key, source, target, curPath)
   ) continue;
`);
    }
    /** ************* copyDescriptors *****************/
    if (options?.copyDescriptors) {
        let scriptL2Descriptors = scriptL1For;
        if (typeof options?.copyDescriptors === 'function') {
            scriptL1For.push('if (copyDescriptorsCallback(key, source, target, curPath)) {');
            scriptL2Descriptors = [];
            scriptL1For.push(scriptL2Descriptors);
            scriptL1For.push(`} else`);
            scriptL1For.push(`  descriptor = {enumerable: true, configurable: true, writable: true}`);
        }
        scriptL2Descriptors.push(`
  descriptor = { ...Object.getOwnPropertyDescriptor(source, key) }
  if ((descriptor.get || descriptor.set)) {
    Object.defineProperty(target, key, descriptor);
    continue;
  }
  srcVal = source[key];`);
    }
    else {
        scriptL1For.push(`descriptor = {enumerable: true, configurable: true, writable: true}`, `srcVal = source[key];`);
    }
    /** ************* keepExisting *****************/
    if (options?.keepExisting) {
        scriptL1For.push(`if (hasOwnProperty.call(target, key)) continue;`);
    }
    /** ************* ignoreUndefined *****************/
    if (options?.ignoreUndefined ?? true) {
        scriptL1For.push(`if (srcVal === undefined) continue;`);
    }
    /** ************* ignoreNulls *****************/
    if (options?.ignoreNulls) {
        scriptL1For.push(`if (srcVal === null) continue;`);
    }
    const deepArray = !options?.moveArrays || typeof options?.moveArrays === 'function';
    /** ************* deep *****************/
    if (options?.deep) {
        if (deepArray) {
            scriptL1For.push(`
_isArray = Array.isArray(srcVal);
if (typeof key !== 'symbol' && (_isArray || deepTest(srcVal))) {`);
        }
        else {
            scriptL1For.push(`
if (typeof key !== 'symbol' && deepTest(srcVal)) {
  subPath = curPath + (curPath ? '.' : '') + key;`);
        }
        scriptL1For.push(`subPath = curPath + (curPath ? '.' : '') + key;`);
        const scriptL2Deep = [];
        scriptL1For.push(scriptL2Deep);
        scriptL1For.push('}');
        let scriptL3Deep = scriptL2Deep;
        if (typeof options?.deep === 'function') {
            scriptL2Deep.push(`
if (deepCallback(key, subPath, target, source)) {`);
            scriptL3Deep = [];
            scriptL2Deep.push(scriptL3Deep);
            scriptL2Deep.push('}');
        }
        /** ************* Array *****************/
        if (!options?.moveArrays || typeof options?.moveArrays === 'function') {
            scriptL3Deep.push(`if (_isArray) {`);
            const scriptL4IsArray = [];
            scriptL3Deep.push(scriptL4IsArray);
            scriptL3Deep.push('}');
            let scriptL5CloneArrays = scriptL4IsArray;
            if (typeof options?.moveArrays === 'function') {
                scriptL4IsArray.push(`
if (moveArraysCallback(key, subPath, target, source)) {
  descriptor.value = srcVal;
  Object.defineProperty(target, key, descriptor);
  continue;
} else {`);
                scriptL5CloneArrays = [];
                scriptL4IsArray.push(scriptL5CloneArrays);
                scriptL4IsArray.push('}');
            }
            scriptL5CloneArrays.push(`
descriptor.value = arrayClone(srcVal, options, merge, subPath);
Object.defineProperty(target, key, descriptor);
continue;
`);
        }
        /** ************* object *****************/
        scriptL3Deep.push(`
trgVal = target[key];
if (!isObject(trgVal)) {
  descriptor.value = trgVal = {};  
  Object.defineProperty(target, key, descriptor);
}
merge(trgVal, srcVal, options, subPath);
continue;`);
    }
    /** ************* finalize *****************/
    scriptL1For.push(`
descriptor.value = srcVal;
Object.defineProperty(target, key, descriptor);`);
    scriptL0.push('return target;');
    const script = _flattenText(scriptL0);
    const fn = Function('target', 'source', 'options', 'curPath', 'context', script);
    context.merge = (target, source, opts, curPath) => fn(target, source, opts, curPath, context);
    return context.merge;
}
function arrayClone(arr, options, _merge, curPath) {
    return arr.map((x) => {
        if (Array.isArray(x))
            return arrayClone(x, options, _merge, curPath);
        if (typeof x === 'object' && !isBuiltIn(x))
            return _merge({}, x, options, curPath);
        return x;
    });
}
function _flattenText(arr, level = 0) {
    const indent = '  '.repeat(level);
    return arr
        .map(v => {
        if (Array.isArray(v))
            return _flattenText(v, level + 1);
        return (indent +
            String(v)
                .trim()
                .replace(/\n/g, '\n' + indent));
    })
        .join('\n');
}