angular2 中 angular.equals 的等价物

Question

我正在将 angular 1 项目迁移到 angular 2 。在 angular 1 项目中，我使用 angular.equals 进行对象比较 angular.equals($ctrl.obj1, $ctrl.newObj); ，我在网上搜索了 angular 2 中的等效方法，但找不到任何匹配的结果。

Answer 1

@Günter 是的，你是对的，在 angular2 中没有等价物。在搜索更多内容时，我发现第三方库 lodash 将与 angular.equals 完成相同的工作，并且语法与 angular one 相同，这个库解决了我的问题

lodash 文档中的代码示例

var object = { 'a': 1 };
var other = { 'a': 1 };
 
_.isEqual(object, other);
// => true
 
object === other;
// => false

Answer 2

我重写了 Ariels 的答案（谢谢！），使其对 TSLINT 友好。您也可以通过使用 else if 来保存一些 continue，但我认为这更清楚。也许其他人也需要它：

export function deepEquals(x, y) {
  if (x === y) {
    return true; // if both x and y are null or undefined and exactly the same
  } else if (!(x instanceof Object) || !(y instanceof Object)) {
    return false; // if they are not strictly equal, they both need to be Objects
  } else if (x.constructor !== y.constructor) {
    // they must have the exact same prototype chain, the closest we can do is
    // test their constructor.
    return false;
  } else {
    for (const p in x) {
      if (!x.hasOwnProperty(p)) {
        continue; // other properties were tested using x.constructor === y.constructor
      }
      if (!y.hasOwnProperty(p)) {
        return false; // allows to compare x[ p ] and y[ p ] when set to undefined
      }
      if (x[p] === y[p]) {
        continue; // if they have the same strict value or identity then they are equal
      }
      if (typeof (x[p]) !== 'object') {
        return false; // Numbers, Strings, Functions, Booleans must be strictly equal
      }
      if (!deepEquals(x[p], y[p])) {
        return false;
      }
    }
    for (const p in y) {
      if (y.hasOwnProperty(p) && !x.hasOwnProperty(p)) {
        return false;
      }
    }
    return true;
  }
}

Answer 3

您可以使用 JSON.stringify 并比较两个字符串，而不是编写一个函数来遍历对象？

例子：

var obj1 = {
  title: 'title1',
  tags: []
}

var obj2 = {
  title: 'title1',
  tags: ['r']
}


console.log(JSON.stringify(obj1));
console.log(JSON.stringify(obj2));


console.log(JSON.stringify(obj1) === JSON.stringify(obj2));

Answer 4

在 Angular 2 中，您应该为此使用纯 JavaScript/TypeScript，以便您可以将此方法添加到某些服务中

private static equals(x, y) {
    if (x === y)
        return true;
    // if both x and y are null or undefined and exactly the same
    if (!(x instanceof Object) || !(y instanceof Object))
        return false;
    // if they are not strictly equal, they both need to be Objects
    if (x.constructor !== y.constructor)
        return false;
    // they must have the exact same prototype chain, the closest we can do is
    // test there constructor.

    let p;
    for (p in x) {
        if (!x.hasOwnProperty(p))
            continue;
        // other properties were tested using x.constructor === y.constructor
        if (!y.hasOwnProperty(p))
            return false;
        // allows to compare x[ p ] and y[ p ] when set to undefined
        if (x[p] === y[p])
            continue;
        // if they have the same strict value or identity then they are equal
        if (typeof (x[p]) !== "object")
            return false;
        // Numbers, Strings, Functions, Booleans must be strictly equal
        if (!RXBox.equals(x[p], y[p]))
            return false;
    }
    for (p in y) {
        if (y.hasOwnProperty(p) && !x.hasOwnProperty(p))
            return false;
    }
    return true;
}

Answer 5

a = { name: 'me' }
b = { name: 'me' }
a == b // false
a === b // false
JSON.stringify(a) == JSON.stringify(b) // true
JSON.stringify(a) === JSON.stringify(b) // true

Answer 6

您可以从 angularjs 复制原始源代码以获取 angular.equals 函数。用法：equals(obj1, obj2);

var toString = Object.prototype.toString;

function isDefined(value) {return typeof value !== 'undefined';}
function isFunction(value) {return typeof value === 'function';}
function createMap() {
  return Object.create(null);
}
function isWindow(obj) {
  return obj && obj.window === obj;
}
function isScope(obj) {
  return obj && obj.$evalAsync && obj.$watch;
}
function isRegExp(value) {
  return toString.call(value) === '[object RegExp]';
}
function simpleCompare(a, b) { return a === b || (a !== a && b !== b); }
function isDate(value) {
  return toString.call(value) === '[object Date]';
}
function isArray(arr) {
  return Array.isArray(arr) || arr instanceof Array;
}
function equals(o1, o2) {
  if (o1 === o2) return true;
  if (o1 === null || o2 === null) return false;
  // eslint-disable-next-line no-self-compare
  if (o1 !== o1 && o2 !== o2) return true; // NaN === NaN
  var t1 = typeof o1, t2 = typeof o2, length, key, keySet;
  if (t1 === t2 && t1 === 'object') {
    if (isArray(o1)) {
      if (!isArray(o2)) return false;
      if ((length = o1.length) === o2.length) {
        for (key = 0; key < length; key++) {
          if (!equals(o1[key], o2[key])) return false;
        }
        return true;
      }
    } else if (isDate(o1)) {
      if (!isDate(o2)) return false;
      return simpleCompare(o1.getTime(), o2.getTime());
    } else if (isRegExp(o1)) {
      if (!isRegExp(o2)) return false;
      return o1.toString() === o2.toString();
    } else {
      if (isScope(o1) || isScope(o2) || isWindow(o1) || isWindow(o2) ||
        isArray(o2) || isDate(o2) || isRegExp(o2)) return false;
      keySet = createMap();
      for (key in o1) {
        if (key.charAt(0) === '$' || isFunction(o1[key])) continue;
        if (!equals(o1[key], o2[key])) return false;
        keySet[key] = true;
      }
      for (key in o2) {
        if (!(key in keySet) &&
            key.charAt(0) !== '$' &&
            isDefined(o2[key]) &&
            !isFunction(o2[key])) return false;
      }
      return true;
    }
  }
  return false;
}