Can anyone explain this bug for me , what we have here is :
有人能给我解释一下这个bug吗?
if(statements[bracket].firsthalf.search(math_operators[j])!=-1)
where statements[bracket].firsthalf = "2*a" , math_operators[j]="*" , the console shows the following error:
语句(支架)。首先，控制台显示如下错误:
Uncaught SyntaxError: Invalid regular expression: /*/: Nothing to repeat
未被捕获的SyntaxError:无效的正则表达式:/*/:不需要重复
any idea why would it show such error ?
知道为什么会出现这样的错误吗?
2 个解决方案
#1
11
Use indexOf, not search. indexOf looks for literal strings, search is for matching a regular expression. In regular expressions, most punctuation characters have special meanings and need to be escaped if you want to find them literally, which is why you're getting errors.
使用indexOf,而不是搜索。indexOf查找字面字符串，搜索是为了匹配正则表达式。在正则表达式中，大多数标点符号都有特殊的含义，如果你想从字面上找到它们，就需要转义，这就是为什么你会出错。
#2
0
Search need a RegularExpression as argument.
搜索需要一个正则表达式作为参数。
* is used to say 0 or more of the previous expression.
*用于表示前一个表达式的0或更多。
Like [0-9]* = 0 or more digits.
比如[0-9]* = 0或更多的数字。
To use * as a character you have to escape it :
要使用*作为一个角色，你必须要避开它:
\*
You have to write the search part as a regular expression.
你必须把搜索部分写成正则表达式。
2*a".search(*) is non sense, because it doesn't search the character (*) but 0 or more time nothing because there is nothing before the *.
2*a“.search(*)”是没有意义的，因为它不搜索字符(*)，而是0或更多的时候什么都没有，因为在*之前什么都没有。
It's the same thing for the + that is protected character too.
同样的道理也适用于受保护字符的+。
You should use another function than search or write your request in a RegularExpression compliant manner like :
您应该使用另一个函数，而不是以符合正则表达式的方式搜索或编写请求:
search([\*|\+|\-|\/])
#1
11
Use indexOf, not search. indexOf looks for literal strings, search is for matching a regular expression. In regular expressions, most punctuation characters have special meanings and need to be escaped if you want to find them literally, which is why you're getting errors.
使用indexOf,而不是搜索。indexOf查找字面字符串，搜索是为了匹配正则表达式。在正则表达式中，大多数标点符号都有特殊的含义，如果你想从字面上找到它们，就需要转义，这就是为什么你会出错。
#2
0
Search need a RegularExpression as argument.
搜索需要一个正则表达式作为参数。
* is used to say 0 or more of the previous expression.
*用于表示前一个表达式的0或更多。
Like [0-9]* = 0 or more digits.
比如[0-9]* = 0或更多的数字。
To use * as a character you have to escape it :
要使用*作为一个角色，你必须要避开它:
\*
You have to write the search part as a regular expression.
你必须把搜索部分写成正则表达式。
2*a".search(*) is non sense, because it doesn't search the character (*) but 0 or more time nothing because there is nothing before the *.
2*a“.search(*)”是没有意义的，因为它不搜索字符(*)，而是0或更多的时候什么都没有，因为在*之前什么都没有。
It's the same thing for the + that is protected character too.
同样的道理也适用于受保护字符的+。
You should use another function than search or write your request in a RegularExpression compliant manner like :
您应该使用另一个函数，而不是以符合正则表达式的方式搜索或编写请求:
search([\*|\+|\-|\/])