private _buildColumns(items : any[], sortedColumn?: IColumn): IColumn[] {
    let columns : IColumn[] = [];
    columns.push({
        key: "editItem",
        name: "",
        fieldName: "",
        minWidth: 25,
        onRender: (item) =>(
          <Link
            data-selection-disabled={ true }
            key={ item }
            href="#"
            onClick={ () => window.location.href = "../SitePages/Test.aspx" }>
          Edit
          </Link>
        )
      });
    return columns;
}

<DetailsList
        items={this.state.items}
        setKey="items"
        selectionPreservedOnEmptyClick={ true }
        columns={this.state.columns}
        layoutMode={DetailsListLayoutMode.justified}
        onRenderMissingItem={(index) => this._onDataMiss}
        selection={this._selection}
        onItemInvoked={this._onItemInvoked}
        onColumnHeaderClick={this._onColumnClick}/>

case 'color':
      return <span data-selection-disabled={ true } style={ { color: fieldContent } }>{ fieldContent }</span>;