How can I improve JSON readability using pretty-printing and syntax highlighting?

Pretty-Printing JSON for Human Readability

Pretty-printing JSON can enhance readability by introducing indentation, whitespace, and potentially colors or font styles. Here are two approaches:

Built-in Pretty-Printing

JavaScript's JSON.stringify() function provides native pretty-printing capabilities. Pass the third argument as a spacing level:

var str = JSON.stringify(obj, null, 2); // spacing level = 2

Syntax Highlighting with Regular Expressions

For syntax highlighting, you can use regular expressions to color-code different JSON elements:

function syntaxHighlight(json) {
  json = json.replace(/&amp;/g, '&amp;amp;').replace(/</g, '&amp;lt;').replace(/>/g, '&amp;gt;');
  return json.replace(/("(\u[a-zA-Z0-9]{4}|\[^u]|[^\"])*"(\s*:)?|\b(true|false|null)\b|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?)/g, function (match) {
    var cls = 'number';
    if (/^"/.test(match)) {
      if (/:$/.test(match)) {
        cls = 'key';
      } else {
        cls = 'string';
      }
    } else if (/true|false/.test(match)) {
      cls = 'boolean';
    } else if (/null/.test(match)) {
      cls = 'null';
    }
    return '<span class="' + cls + '">' + match + '</span>';
  });
}

Complete Example

Here's a full snippet that demonstrates both methods:

<div class="snippet" data-lang="js" data-hide="true" data-console="false" data-babel="false">
  <div class="snippet-code snippet-currently-hidden">
    <pre class="snippet-code-js lang-js prettyprint-override">function output(inp) {
        document.body.appendChild(document.createElement('pre')).innerHTML = inp;
    }

    function syntaxHighlight(json) {
        json = json.replace(/&amp;/g, '&amp;amp;').replace(/</g, '&amp;lt;').replace(/>/g, '&amp;gt;');
        return json.replace(/("(\u[a-zA-Z0-9]{4}|\[^u]|[^\"])*"(\s*:)?|\b(true|false|null)\b|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?)/g, function (match) {
            var cls = 'number';
            if (/^"/.test(match)) {
                if (/:$/.test(match)) {
                    cls = 'key';
                } else {
                    cls = 'string';
                }
            } else if (/true|false/.test(match)) {
                cls = 'boolean';
            } else if (/null/.test(match)) {
                cls = 'null';
            }
            return '<span class="' + cls + '">' + match + '</span>';
        });
    }

    var obj = {a:1, 'b':'foo', c:[false,'false',null, 'null', {d:{e:1.3e5,f:'1.3e5'}}]};
    var str = JSON.stringify(obj, undefined, 4);

    output(str);
    output(syntaxHighlight(str));

pre {outline: 1px solid #ccc; padding: 5px; margin: 5px; }
.string { color: green; }
.number { color: darkorange; }
.boolean { color: blue; }
.null { color: magenta; }
.key { color: red; }