反应this.setState不是一个函数

回调是在不同的上下文中进行的。您需要这样做

bind

this

VK.api('users.get',{fields: 'photo_50'},function(data){    if(data.response){        this.setState({ //the error happens here FirstName: data.response[0].first_name        });        console.info(this.state.FirstName);    }}.bind(this));

编辑：看起来您必须同时绑定

init

api

VK.init(function(){        console.info("API initialisation successful");        VK.api('users.get',{fields: 'photo_50'},function(data){ if(data.response){     this.setState({ //the error happens here         FirstName: data.response[0].first_name     });     console.info(this.state.FirstName); }        }.bind(this));    }.bind(this), function(){    console.info("API initialisation failed");    }, '5.34');