lovecoding
/
W0407


			
				
					
						
						
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							<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #box {
            width: 300px;
            height: 300px;
            background: #00f;
        }
    </style>
</head>

<body>
    <div>
        <div id="box"> </div>
        <br><br>
        <button id="btn1">放大</button>
        <br><br>
        <button id="btn2">缩小</button>
    </div>
    <script>
        var box = document.getElementById("box");
        var btn1 = document.getElementById("btn1");
        var btn2 = document.getElementById("btn2");
        btn1.onclick = function () {
           var timer1 = setInterval(function() {
                if(box.offsetWidth > 500) {
                    clearInterval(timer1);
                } else {
                    box.style.width = box.offsetWidth + 5 + 'px';
                }
            },50)
        }
        btn2.onclick = function() {
           var timer1 = setInterval(function() {
                if(box.offsetWidth <= 300) {
                    clearInterval(timer1);
                } else {
                    box.style.width = box.offsetWidth - 5 + 'px';
                }
            },50)
        }
    </script>
</body>

</html>