返回null的最佳做法是:
未处理异常: RangeError (索引):无效值:不在包含范围0.2
我的代码:
late final int? element;
try {
element = l[index];
} catch(e) {
element = null;
}
寻找一个更短的,一条龙的解决方案。
类似于:
final element = l[index] ?? null;
var map = {
mapSize: 100, // the size of a side
data: new Array(this.mapSize * this.mapSize),
getIndex: function(x, y) {
return x * this.mapSize + y;
},
getCoords: function(index) {
var x = Math.floor(index/this.mapSize);
return {
x: x,
我正在使用react段,在我的.js文件上有
//1. the following is initialised once
let analytics = require('react-segment');
//2. the following is called each time the user does something
analytics.default.load("CODE");
analytics.default.track('EVENT', {});
第一次(2.)称为“页”和“跟踪”事件都被发送到段。第二次只有加载调用(页面