如何在HTML文本框中验证PHP变量名称，如$ as ['abc']

I am trying to validate a user input PHP variable name like $as_cap['abc'] at insert time.

I have to check whether the variable name format is right or wrong. Please help me on that. Curr ently I use

eregi("^[a-z0-9_.'-]{1,50}$")

but it's not working.

regexp that matches your example and its use in javascript:

var checkResult = inputText.match(/\$[a-z_][a-z0-9_]*\[[a-z\']+\]/);

You'll probably need to add global flags and adjust it a bit in case you're using text area and there can be more occurrences of searched assignments