为什么这个正则表达式输出不正确？

Question

var re = /apples/gi;  
var str = "Apples are round, and apples are juicy.";  
var newstr = str.replace("apples", "oranges","gi");
document.write(newstr);

由于不区分大小写，它应该输出oranges are round, and oranges are juicy.，而是输出Apples are round, and oranges are juicy.

为什么？

Answer 1

该签名没有.replace()方法，而是使用您创建的正则表达式，如下所示：

var re = /apples/gi;  
var str = "Apples are round, and apples are juicy.";  
var newstr = str.replace(re, "oranges");

You can test it here

Answer 2

似乎str.replace函数只有two parameters，而不是三个。

所以我猜你必须写

var newstr = str.replace(/apples/gi, "oranges");

代替。

Answer 3

您的示例中的re变量由于某种原因未被使用。

var str = "Apples are round, and apples are juicy.";  
var newstr = str.replace(/apples/gi, "oranges");
document.write(newstr);

Answer 4

尝试：

var str = "Apples are round, and apples are juicy.";  
var newstr = str.replace(/apples/gi, "oranges");
document.write(newstr);

Answer 5

你永远不会使用re变量，而String.replace（）的第三个参数是非标准的，所以它不适用于所有浏览器：

https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/String/replace