JSFiddle - React, Tailwind, and code Playground

JavaScript

var data= 
[
{"id":10,"marks":20},
{"id":20,"marks":30},
{"id":10,"marks":40},
{"id":10,"marks":60},
{"id":10,"marks":70}
];

function getUnique(array) {
    var contains = {},
        unique = [];
        
    for (var i = 0; i < data.length; i++) {
        if(!contains[data[i].id]) {
            contains[data[i].id] = true;
            unique.push(data[i]);
        }
    }
    
    return unique;
}

//console.log(getUnique(data));