Question

我有十个空值

的数组

onTable[0 to 10];

看

["Jean5", "Jean3", "Paul2", "Jean6", "", "Paul4", "Jean", "peirre4", ""]
["Paul5", "peirre6", "peirre3", "", "Jean4", "Paul", "peirre5", "Jean2", ""]
...

我希望获得每个数组的长度而没有空值，并且没有创建十个变量来检查。

我测试了这个解决方案 count empty values in array但我不想让十变量。即：count1, count2,...。

我也检查compare two arrays based on length: skip empty values但不是我想要的。

如果可能的话，我希望看起来像

onTable[0].length(exclude(""))

制作它的好方法是什么？

Answer 1

使用filter与Boolean一起过滤子数组中的非空元素，并在其上使用length。

onTable[0].filter(Boolean).length

由于JavaScript中的空字符串是假的，所以它将从过滤后的数组中删除。

<强>演示：

＆＃13;

var arr = [
  ["Jean5", "Jean3", "Paul2", "Jean6", "", "Paul4", "Jean", "peirre4", ""],
  ["Paul5", "peirre6", "peirre3", "", "Jean4", "Paul", "peirre5", "Jean2", ""]
];

var len = arr[1].filter(Boolean).length;
document.write(len);

＆＃13;

Answer 2

使用prototype：

Array.prototype.lengthWihtoutEmptyValues = function () {
    var initialLength = this.length;
    var finalLength = initialLength;

    for (var i = 0; i < initialLength; i++) {
        if (this[i] == "") {
            finalLength--;
        }
    }

    return finalLength;
}

var arrays = [
  ["Jean5", "Jean3", "Paul2", "Jean6", "", "Paul4", "Jean", "peirre4", ""],
  ["Paul5", "peirre6", "peirre3", "", "Jean4", "Paul", "peirre5", "Jean2", ""]
];

var arrayLength = arrays[0].lengthWihtoutEmptyValues();

$("#arrayLength").html(arrayLength);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="arrayLength"></div>

Answer 3

您可以根据需要使用过滤功能：检查undefined或null等值。

var arr = [
  ["Jean5", "Jean3", "Paul2", "Jean6", "", "Paul4", "Jean", "peirre4", ""],
  ["Paul5", "peirre6", "peirre3", "", "Jean4", "Paul", "peirre5", "Jean2", ""]
];

var len = arr[1].filter(function(x){ return x != ""}).length;
document.write(len);

Answer 4

你应该避免“浪费”记忆并诱导过多的GC。你可以reduce()每个子数组计算它的非空值：

sub.reduce(function(prev, cur) {
  return prev + (!!cur);
}, 0);

为了处理整个主数组，您可以map()使用它的长度：

var arr = [
  ["Jean5", "Jean3", "Paul2", "Jean6", "", "Paul4", "Jean", "peirre4", ""],
  ["Paul5", "peirre6", "peirre3", "", "Jean4", "Paul", "peirre5", "Jean2", ""],
  ["Just1", "", ""]
];

var lengths = arr.map(function(sub) {
  return sub.reduce(function(prev, cur) {
    return prev + (!!cur);
  }, 0);
});
document.write('[' + lengths.join('], [') + ']');

从嵌套数组中获取非空元素的数量

4 个答案: