onfocus="this.value=‘ ‘;"
<input type="text" name="buynum" id="buynum" class="form-control" onkeyup="duihuan()" onfocus="this.value=‘‘;" />
by 小鬼PSer 2018-01-16 15:45:10
onfocus="this.value=‘ ‘;"
<input type="text" name="buynum" id="buynum" class="form-control" onkeyup="duihuan()" onfocus="this.value=‘‘;" />
by 小鬼PSer 2018-01-16 15:45:10
原文：https://www.cnblogs.com/php-qiuwei/p/8297019.html