数组去重的三种方法 es6
[1,2,3,4,5,6,7,8,9,2,2,3,3,4,1].filter(function(el,index,arr){
return (index === arr.indexOf(el));
})
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[1,2,3,4,5,6,7,8,9,2,2,3,3,4,1].filter(function(el,index,arr){
return (index === arr.indexOf(el));
})
