javascript - jQuery $.map 的 Angular 等效项？

Question

我正在从依赖 jQuery 过渡到使用 AngularJS 构建应用程序。在number of places中推荐不要混合使用 jQuery 和 Angular 代码。

我想念的一件事是数组的 jQuery $.map 函数。我知道这可以使用 native Javascript 重写 map function ，但这并未在所有浏览器中实现(尤其是 IE < v9)。

那么，有没有 Angular 的等价物，或者我应该回去写 for (var x = 0; x < foo; x += 1) {...}这样我就可以停止包含 jQuery 了吗？

更新 有时您只需要知道要搜索什么。 Bergie 说“寻找 polyfill”。这是一份引用指南(来自 Modernizr 工作人员)，其中包含大量资源，可让现代代码在旧版浏览器上运行:HTML5 Cross Browser Polyfills

Answer 1

在这里查看:https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Array/map

Mozilla 为不支持的浏览器提供了 Array.map polyfill

if (!Array.prototype.map) {
  Array.prototype.map = function(callback, thisArg) {

    var T, A, k;

    if (this == null) {
      throw new TypeError(" this is null or not defined");
    }

    // 1. Let O be the result of calling ToObject passing the |this| value as the argument.
    var O = Object(this);

    // 2. Let lenValue be the result of calling the Get internal method of O with the argument "length".
    // 3. Let len be ToUint32(lenValue).
    var len = O.length >>> 0;

    // 4. If IsCallable(callback) is false, throw a TypeError exception.
    // See: http://es5.github.com/#x9.11
    if (typeof callback !== "function") {
      throw new TypeError(callback + " is not a function");
    }

    // 5. If thisArg was supplied, let T be thisArg; else let T be undefined.
    if (thisArg) {
      T = thisArg;
    }

    // 6. Let A be a new array created as if by the expression new Array(len) where Array is
    // the standard built-in constructor with that name and len is the value of len.
    A = new Array(len);

    // 7. Let k be 0
    k = 0;

    // 8. Repeat, while k < len
    while(k < len) {

      var kValue, mappedValue;

      // a. Let Pk be ToString(k).
      //   This is implicit for LHS operands of the in operator
      // b. Let kPresent be the result of calling the HasProperty internal method of O with argument Pk.
      //   This step can be combined with c
      // c. If kPresent is true, then
      if (k in O) {

        // i. Let kValue be the result of calling the Get internal method of O with argument Pk.
        kValue = O[ k ];

        // ii. Let mappedValue be the result of calling the Call internal method of callback
        // with T as the this value and argument list containing kValue, k, and O.
        mappedValue = callback.call(T, kValue, k, O);

        // iii. Call the DefineOwnProperty internal method of A with arguments
        // Pk, Property Descriptor {Value: mappedValue, : true, Enumerable: true, Configurable: true},
        // and false.

        // In browsers that support Object.defineProperty, use the following:
        // Object.defineProperty(A, Pk, { value: mappedValue, writable: true, enumerable: true, configurable: true });

        // For best browser support, use the following:
        A[ k ] = mappedValue;
      }
      // d. Increase k by 1.
      k++;
    }

    // 9. return A
    return A;
  };      
}