在vue中获取屏幕宽度的方法有：1.使用document.documentElement方法获取；2.在watch中实时监听；3.使用mounted函数获取；

具体方法如下：

1.使用document.documentElement方法获取屏幕的宽高

windowWidth: document.documentElement.clientWidth, //获取屏幕宽度
windowHeight: document.documentElement.clientHeight, //获取屏幕高度

2.在watch中实时监听屏幕宽高

watch: {
windowHeight (val) {
let that = this;
console.log("实时屏幕高度：",val, that.windowHeight );
},
windowWidth (val) {
let that = this;
console.log("实时屏幕宽度：",val, that.windowHeight );
}
},

3.使用mounted函数获取屏幕宽高

mounted() {
var that = this;
window.onresize = () => {
return (() => {
window.fullHeight = document.documentElement.clientHeight;
window.fullWidth = document.documentElement.clientWidth;
that.windowHeight = window.fullHeight; //获取屏幕高度
that.windowWidth = window.fullWidth; //获取屏幕宽度
})()
};
},