我想优化下面的代码,因为它看起来步骤太多。该代码确实有效,但是我想看看是否有更好的方法。我基本上想从shipmentTracings 数组中获取第一个X 元素和最后一个X 元素。有没有办法优化这部分?
此外,我根据 numberOfTracings/2 导出数组左侧和右侧所需的元素。对于奇数,我将向下舍入,但您可以看到我正在使用 paddingRight 来使用余数,如果有的话。还有更好的方法吗?
const numberOfTracings = environment.shipmentTracingMarkerLimit - this.shipmentTracking.shipmentStops.length; // i.e. 7
const paddingLeft = Math.floor(numberOfTracings / 2);
const paddingRight = numberOfTracings - paddingLeft * 2; //i am doing this because I want to use that extra array spot to be padded. It
const myFirstArr = this.shipmentTracking.shipmentTracings.slice(0, paddingLeft);
const myFirstArr2 = this.shipmentTracking.shipmentTracings.slice(-(paddingLeft + paddingRight));
const myFirstArr3 = myFirstArr.concat(myFirstArr2);
myFirstArr3.forEach((shipmentTracing) => this.createRouteMarkerForTracing(shipmentTracing));
最佳答案
使用评论中的示例,您可以使用 ES2015 spread operator做这样的事情:
const fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"];
const padding = 2;
const firstAndLast = [...fruits.slice(0, padding), ...fruits.slice(-padding)];
console.log(firstAndLast);
编辑:根据基于 padding
计算左/右切片的注释进行更新:
const fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango", "Dragon Fruit", "Kiwi", "Apricot", "Lime", "Plantain"];
const getFirstAndLast = (arr, padding) => {
const left = Math.ceil(padding / 2);
const right = padding - left;
return [...arr.slice(0, left), ...arr.slice(-right)];
};
// gets first 4 and last 3 given a padding of 7
const firstAndLast = getFirstAndLast(fruits, 7);
console.log(firstAndLast);
关于javascript - typescript 从数组的前端和末尾获取 X 个元素,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/55056053/