是否有等效于Array.prototype.find（）的Javascript，可在较旧的浏览器上运行？

Question

Looking at the MDN definition of Array.prototype.find() , I was wondering if there is another javascript method to return the first object from an array based on a predicate, that also works on older browsers.

I am aware of 3rd party libraries such as _underscore and Linq.JS that do this, but curious if there is a more "native" approach.

Answer 1

You can use MDN Polyfill which override this method in old browsers (Read the Tushar's comment).

 if (!Array.prototype.find) {
  Array.prototype.find = function(predicate) {
    if (this === null) {
      throw new TypeError('Array.prototype.find called on null or undefined');
    }
    if (typeof predicate !== 'function') {
      throw new TypeError('predicate must be a function');
    }
    var list = Object(this);
    var length = list.length >>> 0;
    var thisArg = arguments[1];
    var value;

    for (var i = 0; i < length; i++) {
      value = list[i];
      if (predicate.call(thisArg, value, i, list)) {
        return value;
      }
    }
    return undefined;
  };
}

Answer 2

Check this library: https://github.com/iabdelkareem/LINQ-To-JavaScript

It contains what you seek for [firstOrDefault] method for example:

var ar = [{name: "Ahmed", age: 18}, {name: "Mohamed", age:25}, {name:"Hossam", age:27}];
var firstMatch = ar.firstOrDefault(o=> o.age > 20); //Result {name: "Mohamed", age:25}