let txtObj = document.getElementsByClassName('txt')
		for ( let i = 0; i < txtObj.length; i++) {
			txtObj[i].ondragstart = handle_start
			txtObj[i].ondrag = handle_drag
			txtObj[i].ondragend = handle_end
		}
		function handle_start(e) {
			e.dataTransfer.setData('Text', e.target.id)
			console.log('handle_start-拖动开始')
		}
		function handle_drag(e) {
			console.log('handle_drag-拖动中')
		}
		function handle_end(e) {
			console.log('handle_end-拖动结束')
		}

		let target = document.getElementById('right')
		target.ondragenter = handle_enter
		target.ondragover = handle_over
		target.ondragleave = handle_leave
		target.ondrop = handle_drop
		let leftTarget = document.getElementById('left')
		leftTarget.ondragenter = handle_enter
		leftTarget.ondragover = handle_over
		leftTarget.ondragleave = handle_leave
		leftTarget.ondrop = handle_drop

		function handle_enter(e) {
			e.preventDefault()
			console.log('handle_enter-进入目的地')
		}
		function handle_over(e) {
			e.preventDefault()
			let returnObj = e.dataTransfer.getData('Text')
			console.log(returnObj +'-handle_over-在目的地范围内')
		}
		function handle_leave(e) {
			e.preventDefault()
			let returnObj = e.dataTransfer.getData('Text')
			console.log(returnObj)
			console.log('handle_leave-没有放下就离开目的地')
		}
		function handle_drop(e) {
      e.stopPropagation();// 不再派发事件。解决Firefox浏览器，打开新窗口的问题。
			e.preventDefault()
			let returnObj = e.dataTransfer.getData('Text')
			if (returnObj) {
				e.target.appendChild(document.getElementById(returnObj))
			}
			console.log(returnObj + '-handle_drop-在目的地区释放')
		}