Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.1)
// Compass (v1.0.1)
// ----

.selector {
  width:100px;
  height:100px;
  
  .child-selector {
    background-color:blue;
    
    .no-js & {
      background-color:pink;
    }
  }
}

SassMeister-output.css

.selector {
  width: 100px;
  height: 100px;
}
.selector .child-selector {
  background-color: blue;
}
.no-js .selector .child-selector {
  background-color: pink;
}