GAPPs GSheet build data layer push code snippet from list of key/values

Build Data Layer Snippet.gs

/**
 * Generates a JSON or dataLayer.push() snippet per row based on provided keys, values, comments, and an optional filter.
 *
 * Accepts array inputs and returns one dataLayer code block per row.
 * Designed to be used with ARRAYFORMULA or range-based inputs.
 *
 * @customfunction
 * @param {Range} keys A range of keys. Each row represents one variable's key path (e.g. ["ecommerce", "items", "price"]).
 * @param {Range} values A column of values. Each cell corresponds to the value of the key in the same row of the `keys` range.
 * @param {Range} comments Optional. A column of developer comments or descriptions per key.
 * @param {Range} filter Optional. A column of filter groups. For each output row, only includes key/value rows with the same filter value.
 * @return {String[][]} An array of formatted dataLayer.push() blocks, one per row.
 * @example
 * =MY_DATALAYER_CODE_AF(A2:A10, B2:B10, C2:C10, D2:D10)
 */
function MY_DATALAYER_CODE_AF( keys, values, comments, filter ){
  const args = [].slice.apply(arguments);
  return args[0].map( ( _, idx ) =>{
    return [ MY_DATALAYER_CODE( keys, values, comments, filter && /\bSchema\b/.exec(filter[idx]), filter, filter[idx] ) ];
  });
}

function _customFormulaError( msg ){
  return "Error: "+msg;
}

function _foreach( arrOrObj, callback ){
    if( arrOrObj.join )
      return arrOrObj.forEach( ( v, k )=> callback( v, k, { isArray: true, length: arrOrObj.length, index: k } ) );
    let idx = 0;
    Object.entries(arrOrObj).forEach( ([ k, v ])=>{
      callback( v, k, { isArray: false, length: Object.keys(arrOrObj).length, index: idx++ } );
    });
}

function MY_DATALAYER_CODE( keys, values, comments, jsonOnly, filter, filterCondition ){
  let //model = {}, 
    output ='',
    args = [].slice.call(arguments), keyPath;

    const log = function( str ){ output += "\n > "+str+"\n-----"} ;

  const model = {}, total = args[0].length;
  let listArgs = [... args.slice(0,3),... args.slice(4,5)];
  if( !listArgs[0] || !listArgs[0].join ) return _customFormulaError( 'Input must be an array' );
  if( !total ) return _customFormulaError( '(empty)' );
  for( let i=1; i<listArgs.length; i++ ) // create empty arrays for unused optional inputs
    listArgs[i] = listArgs[i] || [...Array(total)].map(e => Array(1));
  if( ! listArgs.every( arg => arg.length === total ) ) 
    return _customFormulaError( 'Inputs must be same length [' +listArgs.map( arg => arg.length).join(",")+']' );
  [ keys, values, comments, filter ] = listArgs;

  keys.forEach( ( keyPath, idx ) => {
    let val = values ? values[idx][0] : "?",
          comment = comments[idx][0];
    let _model = model; 
    keyPath = keys[idx].filter( k => !!k );

    if( !keyPath || ( filter[idx][0] != filterCondition ) ) return;

    keyPath = keyPath.join ? keyPath : [keyPath]; // Convert singular key to a key path array

    //TODO enforce order (i.e. 'event' key first)
    keyPath.forEach( (k,level) => {
      //if( !k ) return; //handled above by .filter( k => !!k )
      // TODO handle merging if already exists // if( _model[k]?.constructor === Object )

      if( level < keyPath.length-1 )
        //return ( _model = ( _model[k] = _model[k] || {} ));
        return ( _model = ( _model[k] = ( _model[k]?.constructor === Object ) ? _model[k] : {} ));

      return ( _model[k] = _model[k] && (_model[k]!=="Object") &&(_model[k]?.val!=="Object") ? _model[k] : ( comment ? { value: val, _dlcode_col_comment: comment } : val ) );
    });
  });

  var _stringifyModel = function( obj, depth ){ // TODO optimize
    let formatKey = k => (k=k+'').match(/^[a-zA-Z0-9_]+$/) ? k : "'"+k+"'";
    let r = [], comment,
        left = obj.join ? '[' : '{', right = obj.join ? ']' : '}';
        newline = '\n'+''.repeat((depth||0)*2);
    try{
      if( typeof obj === "undefined" ){ return "(UNDEFINED)"; };

      if( typeof obj !== "object" || obj === null )
        return ( ["String","Number","Boolean","Date","Object","Array"].includes(obj)
            ? obj
            : JSON.stringify( (()=>{ try{ return JSON.parse( obj ) || obj; }catch(ex){} return obj })() ) );

      // TODO if all obj keys are numeric, parse as array - obj.values()

      _foreach( obj, ( v, k, { isArray, length, index } )=>{

        // r.push( `_foreach (${index}/${length}) [${k}] : ${v} isArray:${isArray} : ${v}` );
        if( 'undefined' === typeof v ) return;
        if( comment = ( v && v._dlcode_col_comment ) )  v = v.value;
        r.push( 
          (isArray
            ? _stringifyModel( v, (depth||0)+1 )
            : formatKey(k)+' : '+_stringifyModel( v, (depth||0)+1 ) )
          +( index === length-1 ? '' : ',' )
          +( comment ? ' // '+comment : '' )
          
        );

      });

      switch( r.length ){
        case 0:  r = left+right; break;
        case 1:
        case 2:  if( jsonOnly ){ 
                  r = left+' '+r.join(' ')+' '+right; break; }
        default: r = left+newline+'  '+r.join(''+newline+'  ')+newline+right; break;
      }

      return r;
    }catch(ex){ r.push( ex+'' ); return r.join("\n"); }
  };

  output += _stringifyModel( model );

  return jsonOnly ? output : '(window.dataLayer=window.dataLayer||[]).push('+output+");";

}