console 命令行工具 X clear

console

window.onload = function() {
    var canvas = document.getElementById("canvas");
    var webgl = canvas.getContext("webgl");
    webgl.viewport(0, 0, canvas.clientWidth, canvas.clientHeight);
    webgl.clearColor(0, 0, 1, 1)
    webgl.clear(webgl.COLOR_BUFFER_BIT)
}

<canvas id="canvas" height="200" width="200"></canvas>