chart.js 2.1

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.5.0/Chart.js"></script>
<canvas id="canvas"></canvas>

JavaScript

var ctx = document.getElementById("canvas").getContext("2d");

		var data = {
		  labels: ['January', 'February', 'March'],
		  datasets: [{
		    data: [1, 2, 3]
		  }]
		};

		var myLineChart = new Chart(ctx, {
		  type: 'line',
		  data: data,
		  options: {
		    showAllTooltips: true,
		    tooltips: {
		      custom: function(tooltip) {
		        if (!tooltip) return;
		        // disable displaying the color box;
		        tooltip.displayColors = false;
		      },
		      callbacks: {
		        // use label callback to return the desired label
		        label: function(tooltipItem, data) {
		          return tooltipItem.xLabel + " :" + tooltipItem.yLabel;
		        },
		        // remove title
		        title: function(tooltipItem, data) {
		          return;
		        }
		      }
		    }
		  }
		});