how to get string from second set of brackets

You can use a greedy .* before matching [ and ] to make sure you are always matching last [...]:

var str = 'services[custom][mainData]'; var result = str.match(/.*\[([^\]\[]*)\]/)[1]; console.log(result); //mainData

RegEx Demo

If the strings are always in that format, you wouldn't really need a complicated regex, you can just split on the ][ and take the remaining string without the last ]. Something like:

id.split('][').pop().slice(0, -1); 

Here's the code with comments for each step:

var id = 'services[custom][mainData]'; var result = id.split('][') // split on `][` gives [ 'services[custom', 'mainData]' ] .pop() // take the last match gives 'mainData]' .slice(0, -1); // trim the last char gives 'mainData' console.log(result); // logs 'mainData'

This regex should do it for you, as long as you catch the right group!

When you want to extract the second pair of brackets, just match the first pair of brackets as well.

var result = id.match(/\[(.*?)\]\[(.*?)\]/); 

With your example of id being services[custom][mainData], result[1] will now be custom and result[2] will be mainData.

This works:

var test = "services[custom][mainData]"; var re = /\[(\w+)\]\[(\w+)\]/g; var res = re.exec(test); document.write(res[2]);