Question

I have a JSON array of this type:

[ 
  { text: '[Chapter1](chapter1.html)'},
  { text: '[Chapter2](chapter2.html)'},
  { text: '[Chapter3](chapter3.html)'},
  { text: '[Chapter4](chapter4.html)'}
]

In an attempt to loop trough the array and fetch the text in brackets (Chapter1, Chapter2, etc) I found a RegExp here at StackOverflow.

var aResponse = JSON.parse(body).desc; // the array described above
var result = []; 
var sectionRegex = /\[(.*?)\]/;
for(var x in aResponse) {
  result.push(sectionRegex.exec(aResponse[x].text));
  //console.log(aResponse[x].text) correctly returns the text value  
}
console.log(result); 

That should print:

["Chapter1","Chapter2","Chapter3","Chapter4"]

However I get weird long results in multiple arrays:

[ '[Chapter1]',
  'Chapter1',
  index: 0,
  input: '[Chapter1](chapter1.html)' ]
[ '[Chapter2]',
  'Chapter2',
  index: 0,
  input: '[Chapter2](chapter2.html)' ]
[ '[Chapter3]',
  'Chapter3',
  index: 0,
  input: '[Chapter3](chapter3.html)' ]
[ '[Chapter4]',
  'Chapter4',
  index: 0,
  input: '[Chapter4](chapter4.html)' ]

What am I missing? I suck at regexps.

Answer 1

The exec method of regular expressions returns not just the matched text but a lot of other information, including the input, match index, matched text, and text of all captured groups. You probably want match group 1:

result.push(sectionRegex.exec(aResponse[x].text)[1]);

Besides that, you shouldn’t use for(...in...) loops to loop over arrays because that will break if any methods are added to Array‘s prototype. (e.g., forEach shims)