ng-style用法

我想给ng-style传一个controller里面的变量，折腾了半天，引号不能忘

ng-style="{'background-color':'{{markColor}}'}"

Since some CSS style names are not valid keys for an object, they must be quoted. See the ‘background-color’ style in the example below.

还有一个问题，string.repalce is not a function，这个貌似是因为要初始化.
myStyle = {};
ng-style=”myStyle”