对象数组，如果key中的value相同，不要该项

	<script type="text/javascript">
	  
	let arr=[
		{
			gradeId: "498094709437239572",
			gradeName: "2018级",
			stageId: "2",
			stageName: "初中",
		},
		{
			gradeId: "498094709437239572",
			gradeName: "2018级",
			stageId: "2",
			stageName: "初中1",
		},
		{
			gradeId: "498094709437239572",
			gradeName: "2018级",
			stageId: "2",
			stageName: "初中2",
		},
		{
			gradeId: "498094709437239572",
			gradeName: "2018级",
			stageId: "2",
			stageName: "初中1",
		},
		{
			gradeId: "498094709437239572",
			gradeName: "2018级",
			stageId: "2",
			stageName: "初中3",
		},
	]
// 先找出不同的阶段，对象数组，如果key中的value相同，不要该项
let newArr=[]
let lastUseArr=[];
for(let i=0;i<arr.length;i++){
	if(newArr.indexOf(arr[i].stageName)==-1){
		 newArr.push(arr[i].stageName)
		 lastUseArr.push(arr[i])
	}
}	 
console.log(lastUseArr)
	  
</script>