Question

嘿，我有一个包含一些空字符串的数组和一些包含内容的字符串。

我想要切掉那些非空字符串的前5个字母，并将它们放入一个新数组中。我也想保留空的。

示例：

myArray = [ "","","123456789","","",""];
var newArray = ["","","12345","","",""]

我尝试使用for循环，如果myArray [i]为空，则不要执行substr（），但是我得到一个错误，它不是函数。

我实际上并不需要将它放入一个新的数组中，我只想将myArray（i）.subsrt（5）值放入splice（）中，但后来我得到了错误：

VM750：82未捕获的TypeError：无法读取属性＆＃39; substr＆＃39;未定义的

Answer 1

如果没有看到所有代码，很难知道你的确切问题是什么，但是这里有一个for循环遍历第一个数组中的所有元素并且每个字符串的前5个或更少字符插入新数组。

myArray = [ "","","123456789","","",""];
var newArray = [];
for(var i = 0; i < myArray.length; i++) {
    newArray.push(myArray[i].substr(0,5));
}

Answer 2

ES6与array.map

myArray = [ "","","123456789","","",""];
var newArray = myArray.map((s) => s.substr(0, 5))

Answer 3

正是@le_m所说的：

myArray = [ "","","123456789","","",""];
var newArray = myArray.map(e => e.substr(0, 5));

Answer 4

您需要将substr用于非空项目：
像这样：

myArray = [ "","","123456789","","",""];
for(var i = 0; i < myArray.length; i++) {
    temp = myArray[i];
    if (temp && temp != "")
      myArray[i] = temp.substr(0, 5);
    else
      myArray[i] = "";
}

如果不是空的，则在数组元素上使用Substr

4 个答案: