Edit in JSFiddle

RESOURCE_NAME = 'target';
API_ROOT = 'https://www.ebi.ac.uk/chembl/api/data/';

function isVowel(c) {
    return ['a', 'e', 'i', 'o', 'u'].indexOf(c.toLowerCase()) !== -1
}

String.prototype.plural = function () {
    	if (this.slice(-1) === 'y') {
    		if ( isVowel(this.charAt(this.length - 2)) )
    			return this + 's';
    		else 
    			return this.slice(0, -1) + 'ies';
    	}
    	else if (this.substring( this.length - 2) === 'us')
    		return this.slice(0, -2) + 'i'; 
    	else if (['ch', 'sh'].indexOf(this.substring( this.length - 2)) !== -1 || ['x','s'].indexOf(this.slice(-1)) !== -1) 
    		return this + 'es';
    	else 		
    		return this + 's';
    }

function render_table(data){
    var table = $('#results');
    var initial_ordering = null;
    var ordering = false;
    for (var i=0; i < data.columns.length; i++){
        if (data.columns[i].orderable){
             initial_ordering = [[i, 'asc']];
             ordering = true;
             break;
         }
    }    
    var dt = table
        .on('xhr.dt', function ( e, settings, json, xhr ) {
            json.recordsTotal = json.page_meta.total_count;
            json.recordsFiltered = json.page_meta.total_count;
        })
        .DataTable({
            "sAjaxDataProp": RESOURCE_NAME.plural(),
            "columns": data.columns,
            "processing": true,
            "serverSide": true,
            "bFilter": false,
            "order": initial_ordering,
            "ordering": ordering,
            "ajax": function(data, callback, settings){
                var url = API_ROOT + RESOURCE_NAME + ".json";
                var ajax_data = {};
                ajax_data.limit = data.length;
                ajax_data.offset = data.start;
                var order = data.order;
                if(order.length){
                    ajax_data.order_by = [];
                    for(var i = 0; i < order.length; i++){
                        console.log(data.columns[order[i].column]);
                        if (!data.columns[order[i].column].orderable){
                            continue;
                        }
                        var ord = data.columns[order[i].column].data.replace(/\./g, '__');
                        if(order[i].dir != 'asc'){
                          ord = '-' + ord;
                        }
                        ajax_data.order_by.push(ord);
                      }
                    }
                    $.ajax({
                        url: url,
                        type: 'POST',
                        data: ajax_data,
                        cache: false,
                        headers: {'X-HTTP-Method-Override': 'GET'},
                        contentType: 'application/x-www-form-urlencoded'
                    }).then(callback); 
                  },            
        });    
}

$(function() {
    $.ajaxSettings.traditional = true;
    $.get(API_ROOT + RESOURCE_NAME + '/datatables.json').then(render_table);
});

<table id="results" width="100%" class="table table-striped table-bordered dataTable" cellspacing="0" role="grid" aria-describedby="example_info" style="width: 100%;">
</table>