获取 tslint 错误：`解析错误：预期表达式`

Question

Can someone shed me some light on this?

I'm getting Failed to compile. Parsing error: Expression expected Failed to compile. Parsing error: Expression expected with this line -

isLogViewVisible: dashboard?.logView !== null where isLogViewVisible is boolean

interface IDashboard {
  logView: ILogView
}

interface ILogView {
  history: string
}

let dashboard: IDashboard | null
let logView: ILogView | null


const someVariable = {
  isLogViewVisible: dashboard?.logView !== null
}

Answer 1

: is for type information, use = for assignment (and === for equality):

isLogViewVisible = state.dashboard?.logView === null

or if you want to make the type explicit (useless here, it is trivially inferred):

const isLogViewVisible: boolean = state.dashboard?.logView === null