Select all text

.js

$('pre code').on('mouseup', function() {
    var sel, range;
    var el = $(this)[0];
    if (window.getSelection && document.createRange) { //Browser compatibility
      sel = window.getSelection();
      if(sel.toString() == ''){ //no text selection
         window.setTimeout(function(){
            range = document.createRange(); //range object
            range.selectNodeContents(el); //sets Range
            sel.removeAllRanges(); //remove all ranges from selection
            sel.addRange(range);//add Range to a Selection.
        },1);
      }
    }else if (document.selection) { //older ie
        sel = document.selection.createRange();
        if(sel.text == ''){ //no text selection
            range = document.body.createTextRange();//Creates TextRange object
            range.moveToElementText(el);//sets Range
            range.select(); //make selection.
        }
    }
});