Example of reducing cyclomatic complexity for more maintainable code.

_before.js

// this function is highly complex. it has a cyclomatic complexity rating of 7.
// it's performance is fine but it's very difficult to read and maintain.
// rating generated by this quick tool: http://jshint.com/
function do_something (config) {
  if (config.prop1) {
    if (config.prop2) {
      if (foo === bar) {
        blah()
      }
    }
  } else {
    if (config.prop3) {
      if (config.prop4) {
        if (foo === bar) {
          blah()
        }
      }
    }
  }
}

after.js

// this function is not very complex. it has a complexity rating of 4.
// moving if statements into null-checks where possible reduces both the complexity and the number of nested blocks.
// i prefer to write null-checks with a comment describing what they do because negating a value tends to make it less easy to interpret.
function do_something_better (config) {
  // don't do this if this prop isn't passed in correctly.
  if (typeof config.prop1 === 'string') { return; }
  // don't do this if this prop isn't passed in correctly.
  if (!config.prop2) { return; }
  // don't do this if this prop isn't passed in correctly.
  if (foo !== bar) { return; }
  
  blah()
}