如何检查JavaScript中是否存在区分大小写和特殊字符的变量中的特定字符串？

Question

I am having string this way,

"The save operation will overwrite [data] in DB;."

I am verifying this way to find is the above string is present in a particular variable.

var myVar  = "The save operation will overwrite [data] in DB;.";
                    var pattern = /The save operation will overwrite [data] in DB;./;
                    var exists = pattern.test(myVar);
                    alert(exists);

why even though pattern and string myVar is matached.. exists is returning false only IN THIS CASE?

I want to exists = true if only if pattern string =='The save operation will overwrite [data] in DB;.'

for rest of all the cases exists should be = false.

ex: The save operation will update/overwrite [data] in DB;. should also return false.

Exist should be true if and only if exactly this pattern is matched. 'The save operation will overwrite [data] in DB;.'

Where exactly I am doing mistake?

Thanks in Advance.

Answer 1

You are using pattern matching, and therfor you should escape special characters ( http://www.regular-expressions.info/refcharacters.html ).

The correct syntax should be

var myVar  = "The save operation will overwrite [data] in DB;.";
                var pattern = /^The save operation will overwrite \[data\] in DB;\.$/;
                var exists = pattern.test(myVar);
                alert(exists);

Note the escape characters before '[', ']' and '.'. ALso the caret '^' tells the line should start there, and the dollar sign '$' the line should end there.

If you want to do case invariant, you can add 'i'. For multiple lines, add 'g'

var myVar  = "The save operation will overwrite [data] in DB;.";
                var pattern = /^The save operation will overwrite \[data\] in DB;\.$/gi;
                var exists = pattern.test(myVar);
                alert(exists);

You can use this site to test regular expressions.

Answer 2

You don't need regular expressions at all here, see below three "match" versions, use the one that fits your requirements:

 var myVar = 'The save operation will overwrite [data] in DB;.'; var pattern = 'The save operation will overwrite [data] in DB;.'; var exists = myVar.indexOf(pattern) > -1; var startsWith = myVar.indexOf(pattern) == 0; var strictEqual = myVar === pattern; alert('Exists: ' + exists + '\\n' + 'Starts with: ' + startsWith + '\\n' + 'Strict equal: ' + strictEqual);