Function _getJsonContentFromDOM

apps/json-format/content-script.js:1194–1241

(dom, parseOptions)

     * 从一个dom节点去获取json内容，这里面有很多的判断
     */
    let _getJsonContentFromDOM = function (dom, parseOptions) {
        if (!document.body) {
            return false;
        }

        let candidates = [];
        let seen = new Set();
        let addCandidate = text => {
            text = (text || '').trim();
            if (text && !seen.has(text)) {
                seen.add(text);
                candidates.push(text);
            }
        };
        let isVisibleElement = elm => elm && elm.nodeType === Node.ELEMENT_NODE && (elm.offsetHeight + elm.offsetWidth !== 0);

        addCandidate(dom && dom.textContent);

        let directText = '';
        Array.from(document.body.childNodes).forEach(elm => {
            if (elm.nodeType === Node.TEXT_NODE) {
                directText += elm.textContent || '';
            }
        });
        addCandidate(directText);

        Array.from(document.querySelectorAll('body>pre')).forEach(elm => addCandidate(elm.textContent));

        if (document.contentType === 'application/json') {
            addCandidate(document.body.innerText);
            Array.from(document.body.children).forEach(elm => {
                const tagName = elm.tagName.toLowerCase();
                if (!['script', 'style', 'link'].includes(tagName) && isVisibleElement(elm)) {
                    addCandidate(elm.innerText || elm.textContent);
                }
            });
        }

        addCandidate(document.body.textContent);

        for (let i = 0; i < candidates.length; i++) {
            if (_parseJsonLike(candidates[i], parseOptions)) {
                return candidates[i];
            }
        }

        return false;
    };

    /**
     * 从页面提取JSON文本