다른 함수 내에서 함수 결과에 액세스하는 중

Question

나는 isRetina 함수를 가지고 있으며 다른 resizeImage() 내에서 결과에 액세스하려고하지만 변수 retinaCheck는 항상 나를 다시 정의하지 않습니다. 글로벌 변수를 처음부터 선언했는데, 왜 그런가?

$(window).load(function() { 
    function isRetina() { 
     return ((window.matchMedia && (window.matchMedia('only screen and (min-resolution: 192dpi), only screen and (min-resolution: 2dppx), only screen and (min-resolution: 75.6dpcm)').matches || window.matchMedia('only screen and (-webkit-min-device-pixel-ratio: 2), only screen and (-o-min-device-pixel-ratio: 2/1), only screen and (min--moz-device-pixel-ratio: 2), only screen and (min-device-pixel-ratio: 2)').matches)) || (window.devicePixelRatio && window.devicePixelRatio > 2)) && /(iPad|iPhone|iPod)/g.test(navigator.userAgent); 
    } 

    var retinaCheck = isRetina(); 

}); 

function resizeImage() { 
    if ($(window).width() > 649) { 
     console.log("resize:" + retinaCheck) 

    } 
}); 

Answer 1

당신은 window.load 외부에서 전역 변수를 선언 할 수 window.load 내부 여기에 값을 할당합니다. resizeImage() 기능을 호출하면 retinaCheck 값을 읽을 수 있습니다.

var retinaCheck; 
$(window).load(function() { 
    function isRetina(){ 
     return ((window.matchMedia && (window.matchMedia('only screen and (min-resolution: 192dpi), only screen and (min-resolution: 2dppx), only screen and (min-resolution: 75.6dpcm)').matches || window.matchMedia('only screen and (-webkit-min-device-pixel-ratio: 2), only screen and (-o-min-device-pixel-ratio: 2/1), only screen and (min--moz-device-pixel-ratio: 2), only screen and (min-device-pixel-ratio: 2)').matches)) || (window.devicePixelRatio && window.devicePixelRatio > 2)) && /(iPad|iPhone|iPod)/g.test(navigator.userAgent); 
    } 

    retinaCheck = isRetina(); 

}); 

function resizeImage() { 
    if ($(window).width() > 649) {   
      console.log("resize:"+retinaCheck)    
     }); 
}