<input type="file" id="file" accept="image/x-wmf" />
<canvas id="canvas"></canvas>

<script>
let wmf = new WMFConverter();   // new the WMFConverter object
	
let canvas = document.getElementById("canvas");
let file = document.getElementById("file");
	
file.onchange = function() {
	let filename = this.files[0];
	wmf.toCanvas(filename, canvas); // load the wmf file and convert to canvas graph
}
</script>