开发vscode插件，怎么实现选中编辑中某个变量呢？

Question

比例想编辑中let name = 'Tom'中的name选中飘红，应该咋做呢？
网上只查到这个代码~~

let decorationType = vscode.window.createTextEditorDecorationType({
            outline: '#00FF00 dotted'
        });
        let editor = vscode.window.activeTextEditor;
        editor.setDecorations(decorationType, [new vscode.Range(5, 1, 1, 4)]);