How to use the @material/linear-progress/index.MDCLinearProgress function in @material/linear-progress

initIndicator = (indicatorEl) => {
    if (!indicatorEl) return;
    const indicator = new MDCLinearProgress(indicatorEl);
    indicator.progress = 0.5;
    this.indicators.push(indicator);
  }

initIndicator = (indicatorEl) => {
    if (!indicatorEl) return;
    this.indicator = new MDCLinearProgress(indicatorEl);
    this.indicator.progress = 0.5;
  }

initBufferIndicator = (indicatorEl) => {
    if (!indicatorEl) return;
    const indicator = new MDCLinearProgress(indicatorEl);
    indicator.progress = 0.5;
    indicator.buffer = 0.75;
    this.indicators.push(indicator);
  }

initLinearProgress = ele => {
    if (!ele) return;
    const indicator = new MDCLinearProgress(ele);
    indicator.progress = 0.5;
    indicator.buffer = 0.75;
    this.componentInstances.push(indicator);
  };
  initRipple = buttonEl => buttonEl && this.componentInstances.push(