Babel构建导致赋值表达式的左侧无效

Question

我不确定我在做什么错，但是当我使用Web pack和babel捆绑代码时。通天塔中的短毛绒猫之一在作业表达式中投掷左手边。我尝试同一行而不进行捆绑，并且没有人抱怨，并且工作正常，不确定是否有人可以提供任何帮助。应该是我想念的小东西。

this.m_checkpointObject.MetaData（key）=值;

这是实际的代码。

如果您将此行放在babel的“试用”页面中，则会引发相同的错误。 https://babeljs.io/repl

class checkPointTimer {
    constructor() { 
        this.m_checkpointObject = null;
        try {
            this.m_checkpointObject = window.external.DiscernObjectFactory("CHECKPOINT");
        } catch (exe) {         
            log.error("Unable to create checkpoint object via window.external.DiscernObjectFactory('CHECKPOINT')");
            return this;
        }
        return this;
    }
    setClassName(className) {
        this.m_checkpointObject && (this.m_checkpointObject.ClassName = className);
        return this;
    };
    setProjectName(projectName) {
        this.m_checkpointObject && (this.m_checkpointObject.ProjectName = projectName);
        return this;
    };
    setEventName(eventName) {
        this.m_checkpointObject && (this.m_checkpointObject.EventName = eventName);
        return this;
    };
    setSubEventName(subEventName) {
        this.m_checkpointObject && (this.m_checkpointObject.SubEventName = subEventName);
        return this;
    };
    publish(){
        this.m_checkpointObject && this.m_checkpointObject.Publish();
    };
    addMetaData(key, value) {
        if (this.m_checkpointObject && key && value){
        try {
            this.m_checkpointObject.MetaData(key) = value
        } catch (e) {
            log.error(e)
            log.error("Error adding MetaData [" + key + "] = " + value + "; on CheckpointTimer");
            return this;
        }
        return this;
        }
    };
}

请帮助！