let arr = left0widthChild200duration2left65widthChild200duration2left65widthChild200duration2

There is a syntax error in the provided array. There is an extra comma after the second object. The corrected array should be:

let arr = [{"left":0,"widthChild":200,"duration":2},{"left":65,"widthChild":200,"duration":2},{"left":65,"widthChild":200,"duration":2}];