如何将空元素推入现有的Js数组中?假设:
var arr = [54,77,21];
var target = [54,77,21,,,,36];
arr.push(); //do not append an empty element into the array.
arr.push();
console.log(JSON.stringify(arr)); //output: [54,77,21]
如何将空元素推入现有的Js数组中?假设:
var arr = [54,77,21];
var target = [54,77,21,,,,36];
arr.push(); //do not append an empty element into the array.
arr.push();
console.log(JSON.stringify(arr)); //output: [54,77,21]
var arr = [54,77,21];
arr[6] = 36;
console.log(JSON.stringify(arr));
undefined
,直到你想要推送这个值。这将返回一个填充好的数组。
var arr = [54,77,21];
arr.push(undefined);
arr.push(undefined);
arr.push(undefined);
arr.push(36);
console.log(JSON.stringify(arr));
JSON.stringify
,你会得到对于未定义或稀疏的项null
,因为JSON只知道null
而不是undefined
。undefined
。稍后解析时没有区别。 - Nina ScholzArray#length
:arr.length++;
var arr = [54,77,21];
arr.length++;
arr.length++;
arr.length++;
arr.push(36);
console.log(arr);
var arr1 = [1, 2, 3, 4];
var arrtarget = [1, 2, 3, 4, , , , 5, 6];
console.log(arr1);
console.log(arrtarget);
newArr = arr1.concat([, , , 5,6]);
console.log(newArr);
另外,您也可以使用 Array.Prototype.push() 方法
arr1.push(undefined);
{0:54, 1: 77, 2: 21, 6: 36}
? - Justinas