在javascript中使用正则表达式找到字符串末尾的匹配项

Question

I have a string for ex "adlkup.db.com" and I want to validate the string for ".com" at the end of the string.

var x = "adlkup.db.com";

So I am trying something like

/.com$/.test(x)

and the . is interpreting to some other regex which finds a single character, except newline or line terminator

Answer 1

A period in a regular expression matches any character.

To make it literal, you need to escape it:

/\.com$/.test('stackoverflow.com'); // true
/\.com$/.test('stackoverflowcom');  // false

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Alternatively, as Racil Hilan points out in the comments , you can also use the .lastIndexOf() method in order to check:

var string = 'stackoverflow.com';
string.lastIndexOf('.com') === string.length - 4; // true

or using the .substr() method :

'stackoverflow.com'.substr(-4) === '.com'; // true

Answer 2

In ECMAScript 6 this is done with endsWith :

x.endsWith(".com");

There is a polyfill for old browsers.

Answer 3

After reading your comments, I think you can use this better than the regex:

 var value1 = "adlkup.db.com"; var value2 = "adlkup.db.com.w3Schools"; var value3 = ".com"; document.write(value1 + " " + endWithCom(value1) + "<br/>"); document.write(value2 + " " + endWithCom(value2) + "<br/>"); document.write(value3 + " " + endWithCom(value3) + "<br/>"); function endWithCom(text){ if(text.length < 5) return false; return (text.substr(-4) == ".com"); } 

And you can easily convert it to generic function so you can pass it any ending you want to check:

 var value1 = "adlkup.db.com"; var value2 = "adlkup.db.com.w3Schools"; var value3 = ".com"; var value4 = "adlkup.db.org"; document.write(value1 + " " + endWithButNotEqual(value1, ".com") + "<br/>"); document.write(value2 + " " + endWithButNotEqual(value2, ".com") + "<br/>"); document.write(value3 + " " + endWithButNotEqual(value3, ".com") + "<br/>"); document.write(value4 + " " + endWithButNotEqual(value4, ".org") + "<br/>"); function endWithButNotEqual(text, ending){ if(text.length <= ending.length) return false; return (text.substr(-ending.length) == ending); }