SOURCE

var app = new Vue({
  el: '#app',
  data () {
    return {
        value: '', //输入中的文字
    }
},
methods: {
    changeInput($event){
        this.value = $event.target.value;
    },
}
})

<!--html-->
<div id="app">
    <div class="textarea-wrapper">
    <!--pre 文本通常会保留空格和换行符。-->
    <div class="content">{{value}}</div>
    <textarea
        v-model="value"
        @input="changeInput($event)"
        placeholder="请在此处输入文字..."
    ></textarea>
</div>
</div>

/* css */
.textarea-wrapper{
    position: relative;
    min-height : 20px;
    width: 100px;
}
.content{
    display: block;
    width: 100%;
    font-size: 14px;
    color: #333333;
    line-height: 1.3;
    word-wrap:break-word;
    font-family: SourceHanSansCN-Regular;
    padding: 0;
}
.textarea-wrapper textarea{
    overflow:hidden;
    resize:none;
    width: 100%;
    height: 100%;
    font-family: SourceHanSansCN-Regular;
    border: 0;
    font-size: 14px;
    color: #333333;
    line-height: 1.3;
    padding: 0px;
    position: absolute;
    left: 0;
    top: 0;
}