label要素と対応するコントロールを表示させる試み。使い方は次のURLを参照：https://github.com/bgrins/devtools-snippets

labelChecker.js

// labelchecker.js
// Forked from formcontrols.js
// https://github.com/bgrins/devtools-snippets
// Print out label and their controls

(function() {

  var forms = document.querySelectorAll("form");

  for (var i = 0, len = forms.length; i < len; i++) {
    var tab = [];

    console.group("HTMLForm quot;" + forms[i].name + "quot;: " + forms[i].action);
    console.log("Element:", forms[i], "\nName:    " + forms[i].name + "\nMethod:  " + forms[i].method.toUpperCase() + "\nAction:  " + forms[i].action || "null");

    ["label"].forEach(function (control) {
      [].forEach.call(forms[i].querySelectorAll(control), function (node) {
        var forAttrVal = node.getAttribute("for");
        var labelTargetElem;
        var labelText;

        if (!forAttrVal) {
          return;
        }

        if (node.firstChild.nodeType === 3) {
          labelText = node.firstChild.nodeValue;
        } else {
          labelText = "";
        }

        labelTargetElem = document.getElementById(forAttrVal);

        tab.push({
          "LabelText": labelText,
          "ForAttributeValue": forAttrVal,
          "TargetControl": labelTargetElem.tagName + "(name: " + labelTargetElem.name + ", value: " + labelTargetElem.value + ")"
        });
      });
    });

    console.table(tab);
    console.groupEnd();
  }
})();