How to use the graphiql/dist/utility/elementPosition.getLeft function in graphiql

let onMouseMove: any = moveEvent => {
      if (moveEvent.buttons === 0) {
        return onMouseUp()
      }

      const app = this.ref
      const cursorPos = moveEvent.clientX - getLeft(app) - offset
      const newSize = app.clientWidth - cursorPos
      const maxSize = window.innerWidth - 50
      const docsSize = maxSize < newSize ? maxSize : newSize

      if (docsSize < 100) {
        this.props.setDocsVisible(
          this.props.sessionId,
          false,
          this.props.docs.activeTabIdx,
        )
      } else {
        this.props.setDocsVisible(
          this.props.sessionId,
          true,
          this.props.docs.activeTabIdx,
        )

private handleDocsResizeStart = downEvent => {
    downEvent.preventDefault()

    const hadWidth = this.props.docs.docsWidth
    const offset = downEvent.clientX - getLeft(downEvent.target)

    let onMouseMove: any = moveEvent => {
      if (moveEvent.buttons === 0) {
        return onMouseUp()
      }

      const app = this.ref
      const cursorPos = moveEvent.clientX - getLeft(app) - offset
      const newSize = app.clientWidth - cursorPos
      const maxSize = window.innerWidth - 50
      const docsSize = maxSize < newSize ? maxSize : newSize

      if (docsSize < 100) {
        this.props.setDocsVisible(
          this.props.sessionId,
          false,

let onMouseMove: any = moveEvent => {
      if (moveEvent.buttons === 0) {
        return onMouseUp()
      }

      const editorBar = ReactDOM.findDOMNode(this.editorBarComponent)
      const leftSize = moveEvent.clientX - getLeft(editorBar) - offset
      const rightSize = editorBar.clientWidth - leftSize
      this.props.setEditorFlex(leftSize / rightSize)
    }

private handleResizeStart = downEvent => {
    if (!this.didClickDragBar(downEvent)) {
      return
    }

    downEvent.preventDefault()

    const offset = downEvent.clientX - getLeft(downEvent.target)

    let onMouseMove: any = moveEvent => {
      if (moveEvent.buttons === 0) {
        return onMouseUp()
      }

      const editorBar = ReactDOM.findDOMNode(this.editorBarComponent)
      const leftSize = moveEvent.clientX - getLeft(editorBar) - offset
      const rightSize = editorBar.clientWidth - leftSize
      this.props.setEditorFlex(leftSize / rightSize)
    }

    let onMouseUp: any = () => {
      document.removeEventListener('mousemove', onMouseMove)
      document.removeEventListener('mouseup', onMouseUp)
      onMouseMove = null