Pretty print a JavaScript Tree Data Structure

gistfile1.js

// Example implementation: http://jsfiddle.net/2f7w2fpn/

var indent = 1;
function walk(tree) {
	tree.forEach(function(node) {
		console.log('--' + Array(indent).join('--'), node.key);
		if(node.children) {
			indent ++;
			walk(node.children);
		}
		if(tree.indexOf(node) === tree.length - 1) {
			indent--;
		}
	})
}

// Usage
walk([
  {
    key: 'fruits',
    children: [
      {
        key: 'apple'
      }, 
      {
        key: 'pear'
      }, 
      {
        key: 'orange'
      }
    ]
  },
  {
    key: 'vegetables',
    children: [
      {
        key: 'carrot',
        children: [
          {
            key: 'orange'
          },
          {
            key: 'red'
          },
          {
            key: 'yellow'
          }
        ]
      },
      {
        key: 'cucumber'
      },
      {
        key: 'tomato'
      }
    ]
  }
]);

// Output
// -- fruits
// ---- apple
// ---- pear
// ---- orange
// -- vegetables
// ---- carrot
// ------ orange
// ------ red
// ------ yellow
// ---- cucumber
// ---- tomato 

Nice, thanks

Thank you! Just what I need.

is there an approach that doesnt include defining the indent outside of the function?

@minmaxdata not sure what you are trying to achieve here, but if you're talking about avoiding creating a global indent variable you could wrap it in another function to create a scope, like so:

function walk(tree) {
  var indent = 1;
  function innerWalk(tree) {
    tree.forEach(function(node) {
      console.log('--' + Array(indent).join('--'), node.key);
      if(node.children) {
        indent ++;
        innerWalk(node.children);
      }
      if(tree.indexOf(node) === tree.length - 1) {
        indent--;
      }
    })
  }
  innerWalk(tree);
}