H5 horizontal and vertical screen detection method

This article mainly introduces in detail the more reliable horizontal and vertical screen detection methods, which has certain reference value. Interested friends can refer to it

Not long ago, I made an H5 project , some processing needs to be done when the horizontal and vertical screens change. There is no doubt that orientationchange needs to be used to monitor changes in horizontal and vertical screens.

Option 1:

// 监听 orientation changes
window.addEventListener("orientationchange", function(event) {
 // 根据event.orientation|screen.orientation.angle等于0|180、90|-90度来判断横竖屏
}, false);

After the code is added, there will be various compatibility issues. The compatibility issues here appear in two places:

orientationchange

##event.orientation |screen.orientation.angle

The following is the compatibility of the orientationchange event:

The following is screen Compatibility of .orientation:

Option 2:

The above solution does not work, so we have to find another way. After google, I learned that it can be achieved through resize (window.inner/outerWidth, window.inner/outerHeight):

window.addEventListener("resize", function(event) {
var orientation=(window.innerWidth > window.innerHeight)? "landscape":"portrait";
if(oritentation === 'portrait'){
// do something ……
} else {
// do something else ……
}
}, false);

This solution basically meets the needs of most projects, but there are still some shortcomings:

As long as the size of the window changes, the resize event will continue to be triggered. You can use setTimeout to optimize it

If you need to monitor horizontal and vertical screens in multiple places, you need to register multiple window.addEventListener("resize", function(event) {......}). Can it be improved through the subscription and publishing model? Only one resize is registered to monitor changes in the horizontal and vertical screens. As long as the horizontal and vertical screen changes, the object of the notification subscription will be published. For other places that need to monitor horizontal and vertical screens, just subscribe.

The key code is as follows:

var resizeCB = function(){
   if(win.innerWidth > win.innerHeight){//初始化判断
    meta.init = 'landscape';
    meta.current = 'landscape';
   } else {
    meta.init = 'portrait';
    meta.current = 'portrait';
   }
   return function(){
    if(win.innerWidth > win.innerHeight){
     if(meta.current !== 'landscape'){
      meta.current = 'landscape';
      event.trigger('__orientationChange__', meta);
     }
    } else {
     if(meta.current !== 'portrait'){
      meta.current = 'portrait';
      event.trigger('__orientationChange__', meta);
     }
    }
   }
  }();

Click here for complete code

Option 3:

But I personally think that through window.innerWidth > What window.innerHeight implements is a kind of pseudo detection, which is a bit unreliable. Is it possible to detect this through a browser? For example, it is implemented based on CSS3@media media query.

The following @media compatibility:

As shown in the picture above, mobile browsers support CSS3 media.

Implementation ideas:

Create a specific css style that identifies the horizontal and vertical screen status

Inject CSS code into the page through JS

Get the status of the horizontal and vertical screens in the resize callback function

Here I select the node font-family of as the detection style attribute.

The reasons are as follows:

Choose mainly to avoid reflow and repaint

Select the font-family style, mainly because font-family has The following features:

• Prioritize using the fonts ranked first.

• If the font cannot be found, or the font does not include the text to be rendered, the next font is used.

• If none of the listed fonts meet your needs, let the operating system decide which font to use.

In this way, we can specify a specific logo to identify the status of the horizontal and vertical screens, but the specified logo needs to be placed in front of other fonts so that it will not cause changes in the hmtl font.

The key code is as follows:

// callback
  var resizeCB = function() {
    var hstyle = win.getComputedStyle(html, null),
      ffstr = hstyle['font-family'],
      pstr = "portrait, " + ffstr,
      lstr = "landscape, " + ffstr,
      // 拼接css
      cssstr = '@media (orientation: portrait) { .orientation{font-family:' + pstr + ';} } @media (orientation: landscape) { .orientation{font-family:' + lstr + ';}}';
    // 载入样式    
    loadStyleString(cssstr);
    // 添加类
    html.className = 'orientation' + html.className;
    if (hstyle['font-family'] === pstr) { //初始化判断
      meta.init = 'portrait';
      meta.current = 'portrait';
    } else {
      meta.init = 'landscape';
      meta.current = 'landscape';
    }
    return function() {
      if (hstyle['font-family'] === pstr) {
        if (meta.current !== 'portrait') {
          meta.current = 'portrait';
          event.trigger('__orientationChange__', meta);
        }
      } else {
        if (meta.current !== 'landscape') {
          meta.current = 'landscape';
          event.trigger('__orientationChange__', meta);
        }
      }
    }
  }();

Click here for complete code

Test effect

portrait effect:

landscape effect:

Option 4:

can be improved again and support

orientationchange, use the native orientationchange. If it is not supported, use option three.

The key code is as follows:

// 是否支持orientationchange事件
var isOrientation = ('orientation' in window && 'onorientationchange' in window);
// callback
var orientationCB = function(e) {
  if (win.orientation === 180 || win.orientation === 0) {
    meta.init = 'portrait';
    meta.current = 'portrait';
  }
  if (win.orientation === 90 || win.orientation === -90) {
    meta.init = 'landscape';
    meta.current = 'landscape';
  }
  return function() {
    if (win.orientation === 180 || win.orientation === 0) {
      meta.current = 'portrait';
    }
    if (win.orientation === 90 || win.orientation === -90) {
      meta.current = 'landscape';
    }
    event.trigger(eventType, meta);
  }
};
var callback = isOrientation ? orientationCB() : (function() {
  resizeCB();
  return function() {
    timer && win.clearTimeout(timer);
    timer = win.setTimeout(resizeCB, 300);
  }
})();
// 监听
win.addEventListener(isOrientation ? eventType : 'resize', callback, false);

Click here for complete code

Option 5:

Currently, the above options are all This is achieved through customized subscription and publishing event patterns. Here you can simulate orientationchange based on the browser's event mechanism. That is to fix the incompatibility of orientationchange.

The key code is as follows:

var eventType = 'orientationchange';
// 触发原生orientationchange
var fire = function() {
  var e;
  if (document.createEvent) {
    e = document.createEvent('HTMLEvents');
    e.initEvent(eventType, true, false);
    win.dispatchEvent(e);
  } else {
    e = document.createEventObject();
    e.eventType = eventType;
    if (win[eventType]) {
      win[eventType]();
    } else if (win['on' + eventType]) {
      win['on' + eventType]();
    } else {
      win.fireEvent(eventType, e);
    }
  }
}

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