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要知道这道题的结果,首先你得知道map方法和parseInt方法:
MDN是这样描述的
map() 方法创建一个新数组,其结果是该数组中的每个元素都调用一个提供的函数后返回的结果。
parseInt() 函数解析一个字符串参数,并返回一个指定基数的整数 (数学系统的基础)。
更多详情点MDN查看
回到正题,上述题目真正执行的代码是这样的:
['1', '2', '3'].map((item, index) => { return parseInt(item, index) })
所以返回值是这样的
parseInt('1', 0) // 1 如果省略第二个参数或其值为 0,则数字将以 10 为基础来解析 parseInt('2', 1) // NaN 第二个参数小于 2 或者大于 36,则 parseInt() 将返回 NaN parseInt('3', 2) // NaN 除了“0、1”外,其它数字都不是有效二进制数字
最后答案即为:
['1', '2', '3'].map(parseInt) // 1, NaN, NaN
The text was updated successfully, but these errors were encountered:
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今天的题目是['1', '2', '3'].map(parseInt)结果是什么?
要知道这道题的结果,首先你得知道map方法和parseInt方法:
MDN是这样描述的
更多详情点MDN查看
回到正题,上述题目真正执行的代码是这样的:
所以返回值是这样的
最后答案即为:
The text was updated successfully, but these errors were encountered: