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用JavaScript實現(xiàn)瀏覽器截圖功能的全過程

更新時間：2025年07月22日 10:33:56 作者：ZCKKKing

在Web開發(fā)中實現(xiàn)網(wǎng)頁截圖功能可以幫助我們保存網(wǎng)頁內(nèi)容、生成海報、制作截圖分享等,這篇文章主要介紹了用JavaScript實現(xiàn)瀏覽器截圖功能的相關(guān)資料,文中通過代碼介紹的非常詳細(xì),需要的朋友可以參考下

HTML部分

截圖開始的按鈕

<button id="start-screenshot" class="button">開始截圖</button>

這里是canvas部分

<div id="screenshot-container">
       <canvas id="screenshot-canvas"></canvas>
       <div class="selection-area" id="selection-area" style="display: none;"></div>
       <div class="toolbar" id="screenshot-toolbar" style="display: none;">
           <button id="confirm-screenshot">確認(rèn)</button>
           <button id="cancel-screenshot">取消</button>
       </div>
</div>

CSS部分

根據(jù)需求自行調(diào)整就好

 #screenshot-container {
     display: none;
     position: fixed;
     top: 0;
     left: 0;
     width: 100%;
     height: 100%;
     z-index: 9999;
 }

 #screenshot-canvas {
     position: absolute;
     top: 0;
     left: 0;
     cursor: crosshair;
 }

 .selection-area {
     position: absolute;
     border: 2px dashed #12B7F5;
     background-color: rgba(18, 183, 245, 0.1);
     pointer-events: none;
 }

 .toolbar {
     position: absolute;
     background-color: white;
     border-radius: 4px;
     box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
     padding: 5px;
     display: flex;
     gap: 5px;
 }

 .toolbar button {
     background-color: #12B7F5;
     color: white;
     border: none;
     padding: 5px 10px;
     border-radius: 4px;
     cursor: pointer;
     font-size: 14px;
 }

 .toolbar button:hover {
     background-color: #0E9AD7;
 }

JS部分（原生JS為例）

獲取dom元素

const startButton = document.getElementById('start-screenshot'); // 開始截圖按鈕
const screenshotContainer = document.getElementById('screenshot-container'); // 獲取的圖片展示區(qū)
const canvas = document.getElementById('screenshot-canvas'); // canvas
const ctx = canvas.getContext('2d');
const selectionArea = document.getElementById('selection-area'); // 截圖區(qū)域
const toolbar = document.getElementById('screenshot-toolbar'); // 截圖時右下角的小彈框
const confirmButton = document.getElementById('confirm-screenshot'); // 確認(rèn)按鈕
const cancelButton = document.getElementById('cancel-screenshot'); // 取消按鈕

變量定義

let isCapturing = false;
let isSelecting = false;
let startX = 0;
let startY = 0;
let endX = 0;
let endY = 0;
let screenCapture = null;

設(shè)置畫布大小

function setCanvasSize() {
    canvas.width = window.innerWidth;
    canvas.height = window.innerHeight;
}

開始截圖方法

async function startScreenshot() {
   try {
       // 請求屏幕捕獲
       screenCapture = await navigator.mediaDevices.getDisplayMedia({
           video: {
               cursor: 'always'
           }
       });

       // 獲取視頻軌道
       const videoTrack = screenCapture.getVideoTracks()[0];
       
       // 創(chuàng)建視頻元素以捕獲屏幕
       const videoElem = document.createElement('video');
       videoElem.srcObject = screenCapture;
       
       // 當(dāng)視頻加載完成后，繪制到畫布上
       videoElem.onloadedmetadata = () => {
           videoElem.play();
           
           // 設(shè)置畫布大小
           setCanvasSize();
           
           // 繪制視頻幀到畫布
           ctx.drawImage(videoElem, 0, 0, canvas.width, canvas.height);
           
           // 停止視頻軌道
           videoTrack.stop();
           
           // 顯示截圖容器
           screenshotContainer.style.display = 'block';
           isCapturing = true;
       };
   } catch (err) {
       console.error('截圖失敗:', err);
       alert('截圖失敗，請確保您已授予屏幕捕獲權(quán)限。');
   }
}

這里會請求屏幕捕獲權(quán)限并獲取屏幕內(nèi)容，這里可以選擇 瀏覽器標(biāo)簽頁、windows打開的窗口、整個屏幕，確實可以獲取到瀏覽器之外的內(nèi)容。

更新選擇區(qū)域

function updateSelectionArea() {
      const width = Math.abs(endX - startX);
      const height = Math.abs(endY - startY);
      const left = Math.min(startX, endX);
      const top = Math.min(startY, endY);

      selectionArea.style.display = 'block';
      selectionArea.style.left = left + 'px';
      selectionArea.style.top = top + 'px';
      selectionArea.style.width = width + 'px';
      selectionArea.style.height = height + 'px';

      // 更新工具欄位置
      toolbar.style.display = 'flex';
      toolbar.style.left = (left + width + 5) + 'px';
      toolbar.style.top = (top + height + 5) + 'px';
}

確認(rèn)截圖（在這里獲取截圖結(jié)果）

function confirmScreenshot() {
    if (!isCapturing) return;

    const width = Math.abs(endX - startX);
    const height = Math.abs(endY - startY);
    const left = Math.min(startX, endX);
    const top = Math.min(startY, endY);

    // 創(chuàng)建新畫布以保存選定區(qū)域
    const resultCanvas = document.createElement('canvas');
    resultCanvas.width = width;
    resultCanvas.height = height;
    const resultCtx = resultCanvas.getContext('2d');

    // 將選定區(qū)域繪制到新畫布
    resultCtx.drawImage(
        canvas,
        left, top, width, height,
        0, 0, width, height
    );

    // 在這里獲取截圖結(jié)果
    // 如果想生成成一個Base64url
    const base64Url = resultCanvas.toDataURL();
	
	// 如果想生成成一個File對象
	const resultFile = dataURLtoFile(resultCanvas.toDataURL(), "截圖.png")
	
    // 重置截圖狀態(tài)
    resetScreenshot();
}

將Base64數(shù)據(jù)轉(zhuǎn)換為File對象（不需要轉(zhuǎn)換結(jié)果為文件對象可以不寫這段）

function dataURLtoFile(dataurl, filename) {
    // 將Base64數(shù)據(jù)拆分為MIME類型和實際數(shù)據(jù)
    const arr = dataurl.split(',');
    const mime = arr[0].match(/:(.*?);/)[1]; // 獲取MIME類型
    const bstr = atob(arr[1]); // 解碼Base64數(shù)據(jù)
    let n = bstr.length;
    const u8arr = new Uint8Array(n);

    // 將解碼后的數(shù)據(jù)轉(zhuǎn)換為Uint8Array
    while (n--) {
        u8arr[n] = bstr.charCodeAt(n);
    }

    // 創(chuàng)建并返回File對象
    return new File([u8arr], filename, { type: mime });
}

取消截圖

function cancelScreenshot() {
    resetScreenshot();
}

重置截圖狀態(tài)

function resetScreenshot() {
   isCapturing = false;
   isSelecting = false;
   selectionArea.style.display = 'none';
   toolbar.style.display = 'none';
   screenshotContainer.style.display = 'none';
   ctx.clearRect(0, 0, canvas.width, canvas.height);
}

各類監(jiān)聽事件

// 事件監(jiān)聽器
startButton.addEventListener('click', startScreenshot);
confirmButton.addEventListener('click', confirmScreenshot);
cancelButton.addEventListener('click', cancelScreenshot);

// 鼠標(biāo)事件處理
canvas.addEventListener('mousedown', function(e) {
    if (!isCapturing) return;

    isSelecting = true;
    startX = e.clientX;
    startY = e.clientY;
    endX = e.clientX;
    endY = e.clientY;
    updateSelectionArea();
});

canvas.addEventListener('mousemove', function(e) {
    if (!isSelecting) return;

    endX = e.clientX;
    endY = e.clientY;
    updateSelectionArea();
});

canvas.addEventListener('mouseup', function() {
    isSelecting = false;
});

// 窗口大小改變時重新設(shè)置畫布大小
window.addEventListener('resize', function() {
    if (isCapturing) {
        setCanvasSize();
    }
});

鍵盤快捷鍵（不需要可以不用）

// 鍵盤快捷鍵
document.addEventListener('keydown', function(e) {
    // Alt + A 開始截圖
    if (e.altKey && e.key === 'a') {
        e.preventDefault();
        startScreenshot();
    }
    
    // Enter 確認(rèn)截圖
    if (e.key === 'Enter' && isCapturing) {
        confirmScreenshot();
    }
    
    // Esc 取消截圖
    if (e.key === 'Escape' && isCapturing) {
        cancelScreenshot();
    }
});

完整代碼

<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>截圖</title>
    <style>
        body {
            margin: 0;
            padding: 0;
            font-family: 'Microsoft YaHei', sans-serif;
            background-color: #f5f5f5;
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            height: 100vh;
            overflow: hidden;
        }

        .container {
            text-align: center;
            background-color: white;
            padding: 30px;
            border-radius: 8px;
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
            max-width: 800px;
            width: 100%;
        }

        .button {
            background-color: #12B7F5;
            color: white;
            border: none;
            padding: 10px 20px;
            border-radius: 4px;
            cursor: pointer;
            font-size: 16px;
            transition: background-color 0.3s;
            margin-top: 10px;
        }

        .button:hover {
            background-color: #0E9AD7;
        }

        #screenshot-container {
            display: none;
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            z-index: 9999;
        }

        #screenshot-canvas {
            position: absolute;
            top: 0;
            left: 0;
            cursor: crosshair;
        }

        .selection-area {
            position: absolute;
            border: 2px dashed #12B7F5;
            background-color: rgba(18, 183, 245, 0.1);
            pointer-events: none;
        }

        .toolbar {
            position: absolute;
            background-color: white;
            border-radius: 4px;
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
            padding: 5px;
            display: flex;
            gap: 5px;
        }

        .toolbar button {
            background-color: #12B7F5;
            color: white;
            border: none;
            padding: 5px 10px;
            border-radius: 4px;
            cursor: pointer;
            font-size: 14px;
        }

        .toolbar button:hover {
            background-color: #0E9AD7;
        }
    </style>
</head>
<body>
    <div class="container">
        <button id="start-screenshot" class="button">開始截圖</button>
    </div>

    <div id="screenshot-container">
        <canvas id="screenshot-canvas"></canvas>
        <div class="selection-area" id="selection-area" style="display: none;"></div>
        <div class="toolbar" id="screenshot-toolbar" style="display: none;">
            <button id="confirm-screenshot">確認(rèn)</button>
            <button id="cancel-screenshot">取消</button>
        </div>
    </div>

    <script>
        document.addEventListener('DOMContentLoaded', function() {
            // 元素引用
            const startButton = document.getElementById('start-screenshot');
            const screenshotContainer = document.getElementById('screenshot-container');
            const canvas = document.getElementById('screenshot-canvas');
            const ctx = canvas.getContext('2d');
            const selectionArea = document.getElementById('selection-area');
            const toolbar = document.getElementById('screenshot-toolbar');
            const confirmButton = document.getElementById('confirm-screenshot');
            const cancelButton = document.getElementById('cancel-screenshot');

            // 截圖狀態(tài)
            let isCapturing = false;
            let isSelecting = false;
            let startX = 0;
            let startY = 0;
            let endX = 0;
            let endY = 0;
            let screenCapture = null;

            // 設(shè)置畫布大小
            function setCanvasSize() {
                canvas.width = window.innerWidth;
                canvas.height = window.innerHeight;
            }

            // 開始截圖
            async function startScreenshot() {
                try {
                    // 請求屏幕捕獲
                    screenCapture = await navigator.mediaDevices.getDisplayMedia({
                        video: {
                            cursor: 'always'
                        }
                    });

                    // 獲取視頻軌道
                    const videoTrack = screenCapture.getVideoTracks()[0];
                    
                    // 創(chuàng)建視頻元素以捕獲屏幕
                    const videoElem = document.createElement('video');
                    videoElem.srcObject = screenCapture;
                    
                    // 當(dāng)視頻加載完成后，繪制到畫布上
                    videoElem.onloadedmetadata = () => {
                        videoElem.play();
                        
                        // 設(shè)置畫布大小
                        setCanvasSize();
                        
                        // 繪制視頻幀到畫布
                        ctx.drawImage(videoElem, 0, 0, canvas.width, canvas.height);
                        
                        // 停止視頻軌道
                        videoTrack.stop();
                        
                        // 顯示截圖容器
                        screenshotContainer.style.display = 'block';
                        isCapturing = true;
                    };
                } catch (err) {
                    console.error('截圖失敗:', err);
                    alert('截圖失敗，請確保您已授予屏幕捕獲權(quán)限。');
                }
            }

            // 更新選擇區(qū)域
            function updateSelectionArea() {
                const width = Math.abs(endX - startX);
                const height = Math.abs(endY - startY);
                const left = Math.min(startX, endX);
                const top = Math.min(startY, endY);

                selectionArea.style.display = 'block';
                selectionArea.style.left = left + 'px';
                selectionArea.style.top = top + 'px';
                selectionArea.style.width = width + 'px';
                selectionArea.style.height = height + 'px';

                // 更新工具欄位置
                toolbar.style.display = 'flex';
                toolbar.style.left = (left + width + 5) + 'px';
                toolbar.style.top = (top + height + 5) + 'px';
            }

            // 將Base64數(shù)據(jù)轉(zhuǎn)換為File對象
            function dataURLtoFile(dataurl, filename) {
                // 將Base64數(shù)據(jù)拆分為MIME類型和實際數(shù)據(jù)
                const arr = dataurl.split(',');
                const mime = arr[0].match(/:(.*?);/)[1]; // 獲取MIME類型
                const bstr = atob(arr[1]); // 解碼Base64數(shù)據(jù)
                let n = bstr.length;
                const u8arr = new Uint8Array(n);

                // 將解碼后的數(shù)據(jù)轉(zhuǎn)換為Uint8Array
                while (n--) {
                    u8arr[n] = bstr.charCodeAt(n);
                }

                // 創(chuàng)建并返回File對象
                return new File([u8arr], filename, { type: mime });
            }

            // 確認(rèn)截圖
            function confirmScreenshot() {
                if (!isCapturing) return;

                const width = Math.abs(endX - startX);
                const height = Math.abs(endY - startY);
                const left = Math.min(startX, endX);
                const top = Math.min(startY, endY);

                // 創(chuàng)建新畫布以保存選定區(qū)域
                const resultCanvas = document.createElement('canvas');
                resultCanvas.width = width;
                resultCanvas.height = height;
                const resultCtx = resultCanvas.getContext('2d');

                // 將選定區(qū)域繪制到新畫布
                resultCtx.drawImage(
                    canvas,
                    left, top, width, height,
                    0, 0, width, height
                );

                // 在這里獲取截圖結(jié)果
                // 如果想生成成一個Base64url
                const base64Url = resultCanvas.toDataURL();
                
                // 如果想生成成一個File對象
                const resultFile = dataURLtoFile(resultCanvas.toDataURL(), "截圖.png")

                // 重置截圖狀態(tài)
                resetScreenshot();
            }

            // 取消截圖
            function cancelScreenshot() {
                resetScreenshot();
            }

            // 重置截圖狀態(tài)
            function resetScreenshot() {
                isCapturing = false;
                isSelecting = false;
                selectionArea.style.display = 'none';
                toolbar.style.display = 'none';
                screenshotContainer.style.display = 'none';
                ctx.clearRect(0, 0, canvas.width, canvas.height);
            }

            // 事件監(jiān)聽器
            startButton.addEventListener('click', startScreenshot);
            confirmButton.addEventListener('click', confirmScreenshot);
            cancelButton.addEventListener('click', cancelScreenshot);

            // 鼠標(biāo)事件處理
            canvas.addEventListener('mousedown', function(e) {
                if (!isCapturing) return;

                isSelecting = true;
                startX = e.clientX;
                startY = e.clientY;
                endX = e.clientX;
                endY = e.clientY;
                updateSelectionArea();
            });

            canvas.addEventListener('mousemove', function(e) {
                if (!isSelecting) return;

                endX = e.clientX;
                endY = e.clientY;
                updateSelectionArea();
            });

            canvas.addEventListener('mouseup', function() {
                isSelecting = false;
            });

            // 鍵盤快捷鍵
            document.addEventListener('keydown', function(e) {
                // Alt + A 開始截圖
                if (e.altKey && e.key === 'a') {
                    e.preventDefault();
                    startScreenshot();
                }
                
                // Enter 確認(rèn)截圖
                if (e.key === 'Enter' && isCapturing) {
                    confirmScreenshot();
                }
                
                // Esc 取消截圖
                if (e.key === 'Escape' && isCapturing) {
                    cancelScreenshot();
                }
            });

            // 窗口大小改變時重新設(shè)置畫布大小
            window.addEventListener('resize', function() {
                if (isCapturing) {
                    setCanvasSize();
                }
            });
        });
    </script>
</body>
</html>