正则表达式单词边界（退格）测试用例

Question

I want to test this condition if the key event is backspace or not:

  if (key.match(/[\b]/)) {
    return true;
  }

where key is coming from keystroke. (like 'a', '6' , '.' etc) What should be the value of key for if condition to return true ?

I tried key as '.' since it is a word boundary (But only with a word, sadly). What should be the key to show backspace <- .

Answer 1

[\\b] matches a backspace character since \\b is inside a character class. To match a word boundary, use /\\b/ (where \\b is not inside a character class):

 var key = "a"; if (/\\b/.test(key)) { // Or, perhaps, for better portability, /[\\x08]/.test(key) alert(true); } 

If you plan to match all non-word characters you just need \\W , not \\b . The word boundary \\b matches a position between ^ and \\w or \\w and $ , or \\W and \\w or \\w and \\W (where \\w stands for a [a-zA-Z0-9_] and \\W stands for any other character not inside these ranges). Also, if you need to match a 1-char string, do not forget anchors: /^\\W$/ .

UPDATE

To test a backspace key, you can use

 var key = "\\x08"; if (/[\\b]/.test(key)) { alert(true); }