变量超出范围

Question

我正在做一个响应式背景视频。 我有这个代码。

<video id="bgvideo" />

function scaleVideo() {

    var windowHeight = $(window).height();
    var windowWidth = $(window).width();

    var videoNativeWidth = $('video#bgvideo')[0].videoWidth;
    var videoNativeHeight = $('video#bgvideo')[0].videoHeight;


    var heightScaleFactor = windowHeight / videoNativeHeight;
    var widthScaleFactor = windowWidth / videoNativeWidth;


    if (widthScaleFactor >= heightScaleFactor) {
        var scale = widthScaleFactor;
    } else {
        var scale = heightScaleFactor;
    }

    var scaledVideoHeight = videoNativeHeight * scale;
    var scaledVideoWidth  = videoNativeWidth * scale;

    $('video#bgvideo').height(scaledVideoHeight);
    $('video#bgvideo').width(scaledVideoWidth);
}

我正在使用grunt来编译我的代码等.Grunt的Jshint说我正在使用“scale”超出范围而我无法理解为什么。

有什么建议？

Answer 1

你不应该写var scale = heightScaleFactor; 如果你想在它之外使用它，在else语句中。

在if之外初始化scale

 var scale;
 if (widthScaleFactor >= heightScaleFactor) {
     scale = widthScaleFactor;
 } else {
     scale = heightScaleFactor;
 }

Answer 2

试试这个：

function scaleVideo() {
    var scale; //this is the change

    var windowHeight = $(window).height();
    var windowWidth = $(window).width();

    var videoNativeWidth = $('video#bgvideo')[0].videoWidth;
    var videoNativeHeight = $('video#bgvideo')[0].videoHeight;


    var heightScaleFactor = windowHeight / videoNativeHeight;
    var widthScaleFactor = windowWidth / videoNativeWidth;


    if (widthScaleFactor >= heightScaleFactor) {
        scale = widthScaleFactor; //simply modify the value here
    } else {
        scale = heightScaleFactor;
    }

    var scaledVideoHeight = videoNativeHeight * scale;
    var scaledVideoWidth  = videoNativeWidth * scale;

    $('video#bgvideo').height(scaledVideoHeight);
    $('video#bgvideo').width(scaledVideoWidth);
}