js设置iframe高度

<iframe id="myIframe" src="example.html" width="100%" height="300px"></iframe>

document.getElementById('myIframe').style.height = '300px';

function setIframeHeight(iframe) {
    if (iframe) {
        var iframeWin = iframe.contentWindow || iframe.contentDocument.defaultView;
        if (iframeWin.document.body) {
            iframe.style.height = iframeWin.document.documentElement.scrollHeight + 'px';
        }
    }
}

window.onload = function() {
    var iframe = document.getElementById('myIframe');
    setIframeHeight(iframe);
};

function observeIframeHeight(iframe) {
    var observer = new MutationObserver(function(mutations) {
        mutations.forEach(function(mutation) {
            setIframeHeight(iframe);
        });
    });

    observer.observe(iframe.contentDocument.body, {
        childList: true,
        subtree: true,
        attributes: true,
        characterData: true
    });
}