Javascript 不同的多个iFrame，跨多个页面？

我的代码在id“greMapTempe”后停止正常运行；我想这是因为它在插入的许多页面中找不到该ID。我加载的iFrame在每个页面上都不同，因此我需要脚本跳过它找不到的ID，然后继续查找下一个ID。我可以对blow代码做什么来确保检查所有ID，即使它们不在页面中

函数loadDeferedFrame（）{
var iframe=document.getElementById（“greYoutube”）；
iframe.src=”https://www.youtube.com/embed/h7_w43jJ0Ts"
var iframe=document.getElementById（“greMapTempe”）；
iframe.src=”https://www.google.com/maps/embed?pb=！1m18！1m12！1m3！1d3330.0372197439724！2d-111.96932568528953！3d33.4222739802116！2m3！1f0！2f0！3m2！1i1024！2i768！4f13.1！3m3！1m2！1s0x0%3A0x0！2ZMZPCSDI1JZIWLJIITAXMTHU4JZAXLIVW！5e0！3m2！1sen！2sus！4V14867741925“
var iframe=document.getElementById（“gremapcinnati”）；
iframe.src=”https://www.google.com/maps/embed?pb=！1m18！1m12！1m3！1d3086.8059851441258！2d-84.4652936843564！3d39.31532112980541！2m3！1f0！2f0！3m2！1i1024！2i768！4f13.1！3m3！1m2！10x88404FB4EC94A687%30x915A9A0DB6E53917！2大+房间+逃生+辛辛那提！5e0！3m2！3m2！1sen！2sus！4V1546663243“
var iframe=document.getElementById（“greMapCleveland”）；
iframe.src=”https://www.google.com/maps/embed?pb=！1m18！1m12！1m3！1d2992.564362618732！2d-81.627932484311！3d41.405266202849035！2m3！1f0！2f0！3m2！1i1024！2i768！4f13.1！3m3！1m2！10x8830E442A6185089%30x90787A2298A6C3C2！2大+房间+逃生+克利夫兰！5e0！3m2！1sen！2sus！4V154144650618“
var iframe=document.getElementById（“greMapColumbus”）；
iframe.src=”https://www.google.com/maps/embed?pb=！1m14！1m8！1m3！1d12214.714268930691！2d-82.9792519！3d40.0602736！3m2！1i1024！2i768！4f13.1！3m3！1m2！1s0x0%3OXD1A0EE0AA5FB171A！2大+房间+逃生+哥伦布！5e0！3m2！1sen！2sus！4V15414463773“
var iframe=document.getElementById（“greMapAustin”）；
iframe.src=”https://www.google.com/maps/embed?pb=！1m18！1m12！1m3！1d3443.8281848309443！2d-97.71271668471364！3d30.32740461210432！2m3！1f0！2f0！3m2！1i1024！2i768！4f13.1！3m3！1m2！1s0x8644ca3ced1c17f7%3A0X7BD80180添加156D1！2sMind+Spark！5e0！3m2！1sen！2sus！4v1472767173729“
var iframe=document.getElementById（“gremapdalas”）；
iframe.src=”https://www.google.com/maps/embed?pb=！1m14！1m8！1m3！1d13390.834398025358！2d-96.7070997！3d32.9587021！3m2！1i1024！2i768！4f13.1！3m3！1m2！1s0x0%3A0897C1A032F856003！2大+房间+逃生+达拉斯！5e0！3m2！1sen！2sus！4V1546025561“
var iframe=document.getElementById（“greSanAntonio”）；
iframe.src=”https://www.google.com/maps/embed?pb=！1m14！1m8！1m3！1d13900.967422077894！2d-98.4774668！3d29.4217269！3m2！1i1024！2i768！4f13.1！3m3！1m2！1s0x0%3A0xfee289ea3851e800！2大+房间+逃生+圣安东尼奥！5e0！3m2！1sen！2sus！4V1545639522“
};
window.onload=loadDeferedFrame在设置src之前检查元素是否存在，否则您将遇到错误，函数的执行将停止


函数loadDeferedFrame（）{
var tryLoadIFrame=函数（ID、URL）{
var iFrame=document.getElementById（ID）；
if（iFrame）{
iFrame.src=URL；
}
}
tryLoadIFrame（“greYoutube”https://www.youtube.com/embed/h7_w43jJ0Ts");
tryLoadIFrame（“greMapTempe”https://www.google.com/maps/embed?pb=！1m18！1m12！1m3！1d3330.0372197439724！2d-111.96932568528953！3d33.4222739802116！2m3！1f0！2f0！3f0！3m2！1i1024！2i768！4f13.1！3m3！1m2！1s0x0%3A0x0！2zmzzpcsdi1jziwljiinitiaxmcsdu4jzaxlivw！5e0！3m2！1sen！2sus！4v148741925”）；
tryLoadIFrame（“Gremapcinnati”https://www.google.com/maps/embed?pb=！1m18！1m12！1m3！1d3086.8059851441258！2d-84.4652936843564！3d39.31532112980541！2m3！1f0！2f0！3m2！1i1024！2i768！4f13.1！3m3！1m2！10x88404FB4EC94A687%30x915A9A0DB6E53917！2大+房间+逃生+辛辛那提！5e0！3m2！1S2！1sen！2sus！4V1546663243”）；
tryLoadIFrame（“greMapCleveland”https://www.google.com/maps/embed?pb=！1m18！1m12！1m3！1d2992.564362618732！2d-81.627932484311！3d41.405266202849035！2m3！1f0！2f0！3m2！1i1024！2i768！4f13.1！3m3！1m2！1s0x8830e442a6185089%3A0x90787a2298a6c3c2！2大+房间+逃生+克利夫兰！5e0！3m2！1sen！2sus！4V154144650618”）；
TRYLADIFRAME（“greMapColumbus”https://www.google.com/maps/embed?pb=！1m14！1m8！1m3！1d12214.714268930691！2d-82.9792519！3d40.0602736！3m2！1i1024！2i768！4f13.1！3m3！1m2！1s0x0%3A0xd1a0ee0aa5fb171a！2大+房间+逃生+哥伦布！5e0！3m2！1sen！2sus！4v1541446346773”）；
TRYLADIFRAME（“Gremapoustin”https://www.google.com/maps/embed?pb=！1m18！1m12！1m3！1d3443.8281848309443！2d-97.71271668471364！3d30.32740461210432！2m3！1f0！2f0！3m2！1i1024！2i768！4f13.1！3m3！1m2！1s0x8644ca3ced1c17f7%3A0X7BD80180180AD156D1！2sMind+Spark！5e0！3m2！1sen！2sus！4v1472767173729”）；
TRYLADIFRAME（“Gremapdalas”https://www.google.com/maps/embed?pb=！1m14！1m8！1m3！1d13390.834398025358！2d-96.7070997！3d32.9587021！3m2！1i1024！2i768！4f13.1！3m3！1m2！1s0x0%3A0897C1A032F856003！2大+房间+逃生+达拉斯！5e0！3m2！1sen！2sus！4V1546025561”）；
tryLoadIFrame（“格雷桑安东尼奥”https://www.google.com/maps/embed?pb=！1m14！1m8！1m3！1d13900.967422077894！2d-98.4774668！3d29.4217269！3m2！1i1024！2i768！4f13.1！3m3！1m2！1s0x0%3A0xfee289ea3851e800！2大+房间+逃生+圣安东尼奥！5e0！3m2！1sen！2sus！4V1545639522”）；
};
window.onload=loadDeferedFrame有多种解决方法：

1-在更改变量的
src
attr之前，检查变量是否不为空：
最基本的方法，但可能是最冗余的（除非您使用像@user1538301的答案这样的帮助函数）：

2-使用jQuery：
使用jQuery按ID（或任何选择器）修改元素不会抛出错误，即使没有匹配项

//will always work, even if there is no match
$("#greYoutube").attr("src", "https://www.youtube.com/embed/h7_w43jJ0Ts");

3-使用ID以外的选择器：
第三种方法的优点是最简洁、最易于维护，因为不需要像iFrame那样多次复制/粘贴

您还可以为要延迟的iframe设置特定的类名
//will always work, even if there is no match
$("#greYoutube").attr("src", "https://www.youtube.com/embed/h7_w43jJ0Ts");

<iframe class='defer' src='someSrc' data-src='https://www.youtube.com/embed/h7_w43jJ0Ts'/>

//this will not throw an error, because if there is no such element, 
//'iframesToDefer' will be empty and thus we won't enter the loop.
var iframesToDefer = document.getElementsByClassName('defer');
for(var iframe of iframesToDefer) {
    iframe.src = iframe.dataset['src'];
}