Javascript catch forEach 最后一次迭代
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/29738535/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
catch forEach last iteration
提问by Jamie Anderson
arr = [1,2,3];
arr.forEach(function(i){
// last iteration
});
How to catch when the loop ending? I can do if(i == 3)but I might don't know what is the number of my array.
循环结束时如何捕捉？我可以做，if(i == 3)但我可能不知道我的阵列的数量是多少。
回答by jdphenix
Updated answer for ES6+ is here.
ES6+ 的更新答案在这里。
arr = [1, 2, 3];
arr.forEach(function(i, idx, array){
if (idx === array.length - 1){
console.log("Last callback call at index " + idx + " with value " + i );
}
});
would output:
会输出：
Last callback call at index 2 with value 3
The way this works is testing arr.lengthagainst the current index of the array, passed to the callback function.
其工作方式是arr.length针对传递给回调函数的数组的当前索引进行测试。
回答by Sterling Bourne
The 2018 ES6+ ANSWER IS:
2018 ES6+ 答案是：
const arr = [1, 2, 3];
arr.forEach((val, key, arr) => {
if (Object.is(arr.length - 1, key)) {
// execute last item logic
console.log(`Last callback call at index ${key} with value ${val}` );
}
});
回答by Justin Coleman
const arr= [1, 2, 3]
arr.forEach(function(element){
if(arr[arr.length-1] === element){
console.log("Last Element")
}
})
