how to combine two array in javascript ? without using underscore : i have two array

    var a=[
	  {_id:1,name:'a'},
	  {_id:2,name:'b'},
	  {_id:3,name:'c'},
    ]

    var b=[
	  {key:1,dis:0.5},
	  {key:2,dis:0.9},
	  {key:3,dis:10}
    ]

from this both there is `_id` and `key` , what i want is if both `_id` and `key` are same than i want one array which look like this

    var result=[
	  {_id:1,name:'a',dis:0.5},
	  {_id:2,name:'b',dis:0.9},
	  {_id:3,name:'c',dis:1},	
    ]

NOTE : i don't want to use any `_` functions similer like `_.map` or `_.extend`

Thanks