if (new_array.indexOf(old_array_value) == -1) new_array.push(old_array_value); return new_array; //最终返回的是 prev value 也就是recorder }, []); 最后把它加入 array的 prototype里面就可以啦 代码: Array.prototype.distinct = function () { return this.reduce(function (new_array, old...
你应该优先使用 dojo 的数组模块,而不是原生 JavaScript 数组函数,原因有很多。Dojo 的数组模块名为dojo/_base/array。 dojo/_base/array 正如您所期望的那样,作为数组模块的一部分,有一个称为forEach()的迭代器方法,以及indexOf()和lastIndexOf()方法。现在来看最好的部分。有一个filter()方法,它返回一个根据...
sort<U>(key: ArrayFunc<T, U>, direction?: "asc" | "desc", comparator?: ArrayComparator<U>): DataArray<T>; groupBy<U>(key: ArrayFunc<T, U>, comparator?: ArrayComparator<U>): DataArray<{ key: U; rows: DataArray<T> }>; distinct<U>(key?: ArrayFunc<T, U>, comparator?: Ar...
This is useful for simple calculations. Popup Element - For conditionally creating popup elements in a layer's popup or a feature reduction popup. This should be used if you want a single expression to return multiple values in a single popup element....
(In the literature, these are sometimes known as “pi nodes.”) Data flow nodes Moving beyond just variable definitions and uses, library semmle.javascript.dataflow.DataFlow provides a representation of the program as a data flow graph. Its nodes are values of class DataFlow::Node, which has ...
The FeatureForm widget now allows you to access data from other layers with FeatureSet functions in field expressions. That means you can derive values based on another layer. For example, you can now calculate fields in a point layer based on values from an intersecting feature in a polygon...
21. Every nth Element in Array Write a JavaScript program to get every nth element in a given array. Click me to see the solution 22. Filter Non-Unique Values in Array Write a JavaScript program to filter out non-unique values in an array. ...
One of the common first questions people ask is "how do I get the latest value of a stream or a property". There is no getLatestValue method available and will not be either. You get the value by subscribing to the stream/property and handling the values in your callback. If you nee...
In case you’re using Set as an intermediate data structure for removing duplicate values from the array, the code can be simplified using underscore or lodash JavaScript libraries. The following example creates a duplicate-free version of an array by using the uniq() function....
Array.prototype.distinct() 在ES6之后,ECMAScript标准库增加了distinct()函数作为实验性特性,但它并没有被官方支持,因此我们不能直接调用它。但是,我们可以自己编写一个简单的distinct()函数,它会遍历整个数组,并检查每个元素是否已经存在于结果集中。如果不存在,则添加到结果集中。 function distinct(arr) { let resu...