var collections = [
 { level: 1, text: 'text' },
 { level: 2, text: 'text2' },
 { level: 1, text: 'text3' },
 { level: 3, text: 'text4' },
 { level: 4, text: 'text5' },
 { level: 3, text: 'text6' },
]

var newCollections = funcFilter(collections, 'level')

newCollections #=> [{ level: 1, text: 'text' }, { level: 1, text: 'text3' }, { level: 3, text: 'text4' }, { level: 3, text: 'text6' }]

function funcFilter(initArray, param){

     var levelValueArray = [];
     var arrToReturn = initArray.filter(function(levelObj){

        var isDuplicate = levelValueArray.some(function(levelValue){
            return levelObj[param] == levelValue
        })

        if (!isDuplicate) {
            levelValueArray.push(levelObj[param]);
            return true
        }
     })

     return arrToReturn
 }