<van-field
value="{{ pwd}}"
placeholder="请输入密码"
border="{{ false }}"
clearable
class="form-input-item"
password="{{passwordShow}}"
icon="{{ passwordShow ? 'closed-eye' : 'eye-o' }}"
bind:input="pwdChange"
bind:click-icon="onClickIcon"
/>
用password属性控制密码的显示与隐藏
不要用type属性，type属性在真机上有时会没有效果
