使用javascript正则表达式从字符串中提取子字符串

Question

I am new to regular expressions in Javascript.

The string looks something like

Password=6)8+Ea:4n+DMtJc:W+*0>(-Y517;Persist Security Info=False;User ID=AppleTurnover;Initial Catalog=ProductDB;Data Source=Sydney

and I am trying to extract from this just the bit

Password=6)8+Ea:4n+DMtJc:W+*0>(-Y517

from ths string.

So, I have:

string="`Password=6)8+Ea:4n+DMtJc:W+*0>(-Y517;Persist Security Info=False;User ID=AppleTurnover;Initial Catalog=ProductDB;Data Source=Sydney"
substring=string.match('/Password=(.*);/g');

It returns back the entire string again. What is going wrong here?

Answer 1

Regex should not be wrapped in quotes. Use [^;]+ to select anything until ; .

var password = string.match(/Password=([^;]+)/)[1];

 string = "`Password=6)8+Ea:4n+DMtJc:W+*0>(-Y517;Persist Security Info=False;User ID=AppleTurnover;Initial Catalog=ProductDB;Data Source=Sydney"; var password = string.match(/Password=([^;]+)/)[1]; document.write(password); 

Or lazy regex can also be used

/Password=(.*?);/g
             ^

 var string = "`Password=6)8+Ea:4n+DMtJc:W+*0>(-Y517;Persist Security Info=False;User ID=AppleTurnover;Initial Catalog=ProductDB;Data Source=Sydney"; var password = string.match(/Password=(.*?);/g); document.write(password); 

Answer 2

It's useful to think of the underlying grammar / syntax:

string := 'Password=' password ';' ...

So you want to match the non-semicolon characters.

string="`Password=6)8+Ea:4n+DMtJc:W+*0>(-Y517;Persist Security Info=False;User ID=AppleTurnover;Initial Catalog=ProductDB;Data Source=Sydney"
/Password=([^;]+)/.exec(string)[0] // or [1] if you want just the password

Answer 3

You could Simply try this /Password.*;/

So you start looking for a String with Password in the beginning, followed by whatever character, until you reach a ; .

By using the g at the end of your RegEx, you are setting it for global, so you are not only looking for the first ; , but for every one. This might have been the reason why yours did not work.

Answer 4

Avoid using potential reserved words.

Your first regular expression worked, you just added useless quote around it. Removig it will works.

var myString = "`Password=6)8+Ea:4n+DMtJc:W+*0>(-Y517;Persist Security Info=False;User ID=AppleTurnover;Initial Catalog=ProductDB;Data Source=Sydney"
var mySubstring = myString.match(/Password=(.*);Persist /g); // Remove the ' around the regex
var thePassword = mySubstring[0].replace('Password=', '');
thePassword = thePassword.replace(';Persist ', '');