code: function getPropIndexes(properties, max, filter) {
    const indexes = [];
  
    try {
      let i = 0;
      for (const name in properties) {
        if (indexes.length >= max) {
          return indexes;
        }
  
        // Type is specified in grip's "class" field and for primitive
        // values use typeof.
        const value = getPropValue(properties[name]);
        let type = value.class || typeof value;
        type = type.toLowerCase();
  
        if (filter(type, value, name)) {
          indexes.push(i);
        }
        i++;
      }
    } catch (err) {
      console.error(err);
    }
    return indexes;
  }
docs: Get the indexes of props in the object.
  
  @param {Object} properties Props object.
  @param {Number} max The maximum length of indexes array.
  @param {Function} filter Filter the props you want.
  @return {Array} Indexes of interesting props in the object.