<script>
var str=‘<p><img style="width: 140px; height: 105px;" src="http://www.mamicode.com/ckfinder/userfiles/images/qi_cym.jpg" data-cke-saved-src="http://www.mamicode.com/ckfinder/userfiles/images/qi_cym.jpg"></p><p><br></p>‘;

var reg = new RegExp("(<img.*src=http://www.mamicode.com/"\.*?\>)"); //正则表达式

str.match(reg);//从字符串str中查找src="http://www.mamicode.com/ckfinder/userfiles/images/qi_cym.jpg"这段字符串

var re = /src="http://www.mamicode.com/([^"]*)"/g; //只查找 /ckfinder/userfiles/images/qi_cym.jpg 这段路径
alert(str.match(reg));
while (arr = re.exec(str)) {
alert(arr[1]);
}
</script>