用JavaScript写一个类似PHP print_r的函数

PHP print_r的函数很好用，网上娱乐城可以用来打印数组、对象等的结构与数据，可惜JavaScript并没有原生提供类似的函数。不过我们可以试着自己来实现这个函数，下面提供一些方法与思路。

方法一

function print_r(theObj) {
    var retStr = ‘‘;
    if (typeof theObj == ‘object‘) {
        retStr += ‘<div style="font-family:Tahoma; font-size:7pt;">‘;
        for (var p in theObj) {
            if (typeof theObj[p] == ‘object‘) {
                retStr += ‘<div><b>[‘+p+‘] => ‘ + typeof(theObj) + ‘</b></div>‘;
                retStr += ‘<div style="padding-left:25px;">‘ + print_r(theObj[p]) + ‘</div>‘;
            } else {
                retStr += ‘<div>[‘+p+‘] => <b>‘ + theObj[p] + ‘</b></div>‘;
            }
        }
        retStr += ‘</div>‘;
    }
    return retStr;
}

方法二

$(document).ready(function(){
	$(‘#btn‘).click(function(){
	  var jsonStr = $(‘#jsonData‘).val();
	  var json = eval(‘(‘+jsonStr+‘)‘);
	  (function(){
		var print_r = function(o, depth) {
		  var result = ‘‘;
		  depth || (depth=1);
		  var indent = new Array(4*depth+1).join(‘ ‘);
		  var indentNext = new Array(4*(depth+1)+1).join(‘ ‘);
		  var indentNextTwo = new Array(4*(depth+2)+1).join(‘ ‘);
		  var tmp = ‘‘;
		  var type = typeof o;
		  switch(type) {
			case ‘string‘:
			case ‘number‘:
			case ‘boolean‘:
			case ‘undefined‘:
			case ‘function‘:
			  tmp += indent + indentNext + o + "\n";
			  break;
			case ‘object‘:
			default:
			  for(var key in o) {
				tmp += indentNextTwo + ‘[‘ + key + ‘] = ‘;
				tmp += print_r(o[key], (depth+1));
			  }
		  }
		  result += type + "\n";
		  result += indentNext + ‘(‘ + "\n";
		  result += tmp;
		  result += indentNext + ‘)‘ + "\n";
		  return result;
		};
		alert(print_r(json));
	  }(json));
	});
});

方法三

print_r:function(theObj) {
	var retStr = ‘‘;
	if (typeof theObj == ‘object‘||typeof theObj == ‘array‘) {
		retStr += ‘<div style="font-family:Tahoma; font-size:7pt;">‘;
		for (var p in theObj) {
			if (typeof theObj[p] == ‘object‘ || typeof theObj[p] == ‘array‘) {
				retStr += ‘<div><b>[‘+p+‘] => ‘ + typeof(theObj) + ‘</b></div>‘;
				retStr += ‘<div style="padding-left:25px;">‘ + XFUPLOAD.Tools.print_r(theObj[p]) + ‘</div>‘;
			} else {
				retStr += ‘<div>[‘+p+‘] => <b>‘ + theObj[p] + ‘</b></div>‘;
			}
		}
		retStr += ‘</div>‘;
	}
	$("body").append(retStr);
}