TypeScript入門 Tips

npm list -g typescript
/Users/yuta/.nodebrew/node/v10.17.0/lib
└── typescript@3.8.3 

tsc --version
Version 3.8.3

function waite(duration: number) {
    return new Promise(resolve => {
        setTimeout(()=> resolve(`${duration} ms passed`), duration)
    })
}
waite(100).then((result) => {}) //resは{}

'Promise' only refers to a type, but is being used as a value here. Do you need to change your target library? Try changing the `lib` compiler option to es2015 or later

npm list -g typescript
/Users/yuta/.nodebrew/node/v10.17.0/lib
└── typescript@3.8.3