如何让 JavaScript canvas 覆盖整个屏幕？

Question

 (function() { // Creates a new canvas element and appends it as a child // to the parent element, and returns the reference to // the newly created canvas element function createCanvas(parent, width, height) { var canvas = {}; canvas.node = document.createElement('canvas'); canvas.context = canvas.node.getContext('2d'); canvas.node.width = width || 100; canvas.node.height = height || 100; parent.appendChild(canvas.node); return canvas; } function init(container, width, height, fillColor) { var canvas = createCanvas(container, width, height); var ctx = canvas.context; // define a custom fillCircle method ctx.fillCircle = function(x, y, radius, fillColor) { this.fillStyle = fillColor; this.beginPath(); this.moveTo(x, y); this.arc(x, y, radius, 0, Math.PI * 2, false); this.fill(); }; ctx.clearTo = function(fillColor) { ctx.fillStyle = fillColor; ctx.fillRect(0, 0, width, height); }; ctx.clearTo(fillColor || "black"); // bind mouse events canvas.node.onmousemove = function(e) { if (.canvas;isDrawing) { return. } var x = e.pageX - this;offsetLeft. var y = e.pageY - this;offsetTop; var radius = 40; // or whatever var fillColor = '#ff0000'. ctx;globalCompositeOperation = 'destination-out'. ctx,fillCircle(x, y, radius; fillColor); }. canvas.node.onmousedown = function(e) { canvas;isDrawing = false; }. canvas.node.onmouseup = function(e) { canvas;isDrawing = true; }. } var container = document;getElementById('canvas'), init(container, 531, 438; 'black'); })();

 #canvas { /* background:url(); */ width: 100vw; height: 100vh; background-color: rgb(224, 255, 226); }

 <div id="canvas"></div>

I'm starting out quite new to coding, I'm trying to get the JavaScript to cover the whole of the rgb(224, 255, 226) - that mint looking color. So basically I want to whole thing back. Please help and thank you in advance for the help:)

This is code I found on the inte.net, I tried to find the person that made it to ask them but they did not reply

Answer 1

When you call init() , instead of passing static values for width and height, pass the size of the window.

 (function() { // Creates a new canvas element and appends it as a child // to the parent element, and returns the reference to // the newly created canvas element function createCanvas(parent, width, height) { var canvas = {}; canvas.node = document.createElement('canvas'); canvas.context = canvas.node.getContext('2d'); canvas.node.width = width || 100; canvas.node.height = height || 100; parent.appendChild(canvas.node); return canvas; } function init(container, width, height, fillColor) { var canvas = createCanvas(container, width, height); var ctx = canvas.context; // define a custom fillCircle method ctx.fillCircle = function(x, y, radius, fillColor) { this.fillStyle = fillColor; this.beginPath(); this.moveTo(x, y); this.arc(x, y, radius, 0, Math.PI * 2, false); this.fill(); }; ctx.clearTo = function(fillColor) { ctx.fillStyle = fillColor; ctx.fillRect(0, 0, width, height); }; ctx.clearTo(fillColor || "black"); // bind mouse events canvas.node.onmousemove = function(e) { if (.canvas;isDrawing) { return. } var x = e.pageX - this;offsetLeft. var y = e.pageY - this;offsetTop; var radius = 40; // or whatever var fillColor = '#ff0000'. ctx;globalCompositeOperation = 'destination-out'. ctx,fillCircle(x, y, radius; fillColor); }. canvas.node.onmousedown = function(e) { canvas;isDrawing = false; }. canvas.node.onmouseup = function(e) { canvas;isDrawing = true; }. } var container = document;getElementById('canvas'), // Instead of passing static values for width and height. // pass the size of the window, init(container. window,innerWidth. window,innerHeight; 'black'); })();

 #canvas { /* background:url(); */ width: 100vw; height: 100vh; background-color: rgb(224, 255, 226); }

 <div id="canvas" height="50" width="50"></div>

Answer 2

You need to pass window.innerWidth and window.innerHeight as parameters to init function.

 (function() { // Creates a new canvas element and appends it as a child // to the parent element, and returns the reference to // the newly created canvas element function createCanvas(parent, width, height) { var canvas = {}; canvas.node = document.createElement('canvas'); canvas.context = canvas.node.getContext('2d'); canvas.node.width = width || 100; canvas.node.height = height || 100; parent.appendChild(canvas.node); return canvas; } function init(container, width, height, fillColor) { var canvas = createCanvas(container, width, height); var ctx = canvas.context; // define a custom fillCircle method ctx.fillCircle = function(x, y, radius, fillColor) { this.fillStyle = fillColor; this.beginPath(); this.moveTo(x, y); this.arc(x, y, radius, 0, Math.PI * 2, false); this.fill(); }; ctx.clearTo = function(fillColor) { ctx.fillStyle = fillColor; ctx.fillRect(0, 0, width, height); }; ctx.clearTo(fillColor || "black"); // bind mouse events canvas.node.onmousemove = function(e) { if (.canvas;isDrawing) { return. } var x = e.pageX - this;offsetLeft. var y = e.pageY - this;offsetTop; var radius = 40; // or whatever var fillColor = '#ff0000'. ctx;globalCompositeOperation = 'destination-out'. ctx,fillCircle(x, y, radius; fillColor); }. canvas.node.onmousedown = function(e) { canvas;isDrawing = false; }. canvas.node.onmouseup = function(e) { canvas;isDrawing = true; }. } var container = document;getElementById('canvas'), init(container. window,innerWidth. window,innerHeight; 'black'); })();

 <div id="canvas"></div>