我想看看JavaScript对象的结构(用于调试)。PHP中有类似var_dump的东西吗?
当前回答
大多数现代浏览器在开发人员工具中都有一个控制台，这对这种调试很有用。
console.log(myvar);
然后你将在控制台中得到对象/任何东西的良好映射接口。
查看控制台文档了解更多详细信息。
其他回答
在JavaScript中等效的var_dump ?很简单，没有。
但这并不意味着你就无能为力了。就像一些人建议的那样，使用Firebug(或其他浏览器中的等效工具)，但与其他人建议的不同的是，当你有(稍微)更好的工具console.dir时，不要使用console.log:
console.dir(object)
打印对象的所有属性的交互式列表。这 看起来与您在DOM选项卡中看到的视图相同。
大多数现代浏览器在开发人员工具中都有一个控制台，这对这种调试很有用。
console.log(myvar);
然后你将在控制台中得到对象/任何东西的良好映射接口。
查看控制台文档了解更多详细信息。
Firebug。
然后，在javascript中:
var blah = {something: 'hi', another: 'noway'};
console.debug("Here is blah: %o", blah);
现在你可以查看控制台，点击语句，看看里面有什么
正如其他人已经提到的，调试变量的最好方法是使用现代浏览器的开发控制台(例如Chrome开发工具，Firefox+Firebug, Opera Dragonfly(现在在新的基于Chrome的(Blink) Opera中消失了，但正如开发人员所说，“蜻蜓没有死，尽管我们还不能给你更多信息”)。
但如果你需要另一种方法，有一个非常有用的网站叫 php.js:
http://phpjs.org/
它提供了“PHP函数的JavaScript替代品”——所以你可以像在PHP中一样使用它们。我将在这里复制粘贴适当的函数给你，但请注意，这些代码可以在原始网站上更新，以防检测到一些错误，所以我建议你访问phpjs.org网站!(顺便说一句。我不是这个网站的会员，但我觉得它非常有用。)
JavaScript中的var_dump()
下面是JS-alternative of var_dump()的代码: http://phpjs.org/functions/var_dump/ 这取决于echo()函数:http://phpjs.org/functions/echo/
function var_dump() {
// discuss at: http://phpjs.org/functions/var_dump/
// original by: Brett Zamir (http://brett-zamir.me)
// improved by: Zahlii
// improved by: Brett Zamir (http://brett-zamir.me)
// depends on: echo
// note: For returning a string, use var_export() with the second argument set to true
// test: skip
// example 1: var_dump(1);
// returns 1: 'int(1)'
var output = '',
pad_char = ' ',
pad_val = 4,
lgth = 0,
i = 0;
var _getFuncName = function(fn) {
var name = (/\W*function\s+([\w\$]+)\s*\(/)
.exec(fn);
if (!name) {
return '(Anonymous)';
}
return name[1];
};
var _repeat_char = function(len, pad_char) {
var str = '';
for (var i = 0; i < len; i++) {
str += pad_char;
}
return str;
};
var _getInnerVal = function(val, thick_pad) {
var ret = '';
if (val === null) {
ret = 'NULL';
} else if (typeof val === 'boolean') {
ret = 'bool(' + val + ')';
} else if (typeof val === 'string') {
ret = 'string(' + val.length + ') "' + val + '"';
} else if (typeof val === 'number') {
if (parseFloat(val) == parseInt(val, 10)) {
ret = 'int(' + val + ')';
} else {
ret = 'float(' + val + ')';
}
}
// The remaining are not PHP behavior because these values only exist in this exact form in JavaScript
else if (typeof val === 'undefined') {
ret = 'undefined';
} else if (typeof val === 'function') {
var funcLines = val.toString()
.split('\n');
ret = '';
for (var i = 0, fll = funcLines.length; i < fll; i++) {
ret += (i !== 0 ? '\n' + thick_pad : '') + funcLines[i];
}
} else if (val instanceof Date) {
ret = 'Date(' + val + ')';
} else if (val instanceof RegExp) {
ret = 'RegExp(' + val + ')';
} else if (val.nodeName) {
// Different than PHP's DOMElement
switch (val.nodeType) {
case 1:
if (typeof val.namespaceURI === 'undefined' || val.namespaceURI === 'http://www.w3.org/1999/xhtml') {
// Undefined namespace could be plain XML, but namespaceURI not widely supported
ret = 'HTMLElement("' + val.nodeName + '")';
} else {
ret = 'XML Element("' + val.nodeName + '")';
}
break;
case 2:
ret = 'ATTRIBUTE_NODE(' + val.nodeName + ')';
break;
case 3:
ret = 'TEXT_NODE(' + val.nodeValue + ')';
break;
case 4:
ret = 'CDATA_SECTION_NODE(' + val.nodeValue + ')';
break;
case 5:
ret = 'ENTITY_REFERENCE_NODE';
break;
case 6:
ret = 'ENTITY_NODE';
break;
case 7:
ret = 'PROCESSING_INSTRUCTION_NODE(' + val.nodeName + ':' + val.nodeValue + ')';
break;
case 8:
ret = 'COMMENT_NODE(' + val.nodeValue + ')';
break;
case 9:
ret = 'DOCUMENT_NODE';
break;
case 10:
ret = 'DOCUMENT_TYPE_NODE';
break;
case 11:
ret = 'DOCUMENT_FRAGMENT_NODE';
break;
case 12:
ret = 'NOTATION_NODE';
break;
}
}
return ret;
};
var _formatArray = function(obj, cur_depth, pad_val, pad_char) {
var someProp = '';
if (cur_depth > 0) {
cur_depth++;
}
var base_pad = _repeat_char(pad_val * (cur_depth - 1), pad_char);
var thick_pad = _repeat_char(pad_val * (cur_depth + 1), pad_char);
var str = '';
var val = '';
if (typeof obj === 'object' && obj !== null) {
if (obj.constructor && _getFuncName(obj.constructor) === 'PHPJS_Resource') {
return obj.var_dump();
}
lgth = 0;
for (someProp in obj) {
lgth++;
}
str += 'array(' + lgth + ') {\n';
for (var key in obj) {
var objVal = obj[key];
if (typeof objVal === 'object' && objVal !== null && !(objVal instanceof Date) && !(objVal instanceof RegExp) &&
!
objVal.nodeName) {
str += thick_pad + '[' + key + '] =>\n' + thick_pad + _formatArray(objVal, cur_depth + 1, pad_val,
pad_char);
} else {
val = _getInnerVal(objVal, thick_pad);
str += thick_pad + '[' + key + '] =>\n' + thick_pad + val + '\n';
}
}
str += base_pad + '}\n';
} else {
str = _getInnerVal(obj, thick_pad);
}
return str;
};
output = _formatArray(arguments[0], 0, pad_val, pad_char);
for (i = 1; i < arguments.length; i++) {
output += '\n' + _formatArray(arguments[i], 0, pad_val, pad_char);
}
this.echo(output);
}
JavaScript中的print_r()
下面是print_r()函数: http://phpjs.org/functions/print_r/ 它也依赖于echo()。
function print_r(array, return_val) {
// discuss at: http://phpjs.org/functions/print_r/
// original by: Michael White (http://getsprink.com)
// improved by: Ben Bryan
// improved by: Brett Zamir (http://brett-zamir.me)
// improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
// input by: Brett Zamir (http://brett-zamir.me)
// depends on: echo
// example 1: print_r(1, true);
// returns 1: 1
var output = '',
pad_char = ' ',
pad_val = 4,
d = this.window.document,
getFuncName = function(fn) {
var name = (/\W*function\s+([\w\$]+)\s*\(/)
.exec(fn);
if (!name) {
return '(Anonymous)';
}
return name[1];
};
repeat_char = function(len, pad_char) {
var str = '';
for (var i = 0; i < len; i++) {
str += pad_char;
}
return str;
};
formatArray = function(obj, cur_depth, pad_val, pad_char) {
if (cur_depth > 0) {
cur_depth++;
}
var base_pad = repeat_char(pad_val * cur_depth, pad_char);
var thick_pad = repeat_char(pad_val * (cur_depth + 1), pad_char);
var str = '';
if (typeof obj === 'object' && obj !== null && obj.constructor && getFuncName(obj.constructor) !==
'PHPJS_Resource') {
str += 'Array\n' + base_pad + '(\n';
for (var key in obj) {
if (Object.prototype.toString.call(obj[key]) === '[object Array]') {
str += thick_pad + '[' + key + '] => ' + formatArray(obj[key], cur_depth + 1, pad_val, pad_char);
} else {
str += thick_pad + '[' + key + '] => ' + obj[key] + '\n';
}
}
str += base_pad + ')\n';
} else if (obj === null || obj === undefined) {
str = '';
} else {
// for our "resource" class
str = obj.toString();
}
return str;
};
output = formatArray(array, 0, pad_val, pad_char);
if (return_val !== true) {
if (d.body) {
this.echo(output);
} else {
try {
// We're in XUL, so appending as plain text won't work; trigger an error out of XUL
d = XULDocument;
this.echo('<pre xmlns="http://www.w3.org/1999/xhtml" style="white-space:pre;">' + output + '</pre>');
} catch (e) {
// Outputting as plain text may work in some plain XML
this.echo(output);
}
}
return true;
}
return output;
}
JavaScript中的var_export()
你可能还会发现var_export()替代方法很有用，它也依赖于echo(): http://phpjs.org/functions/var_export/
function var_export(mixed_expression, bool_return) {
// discuss at: http://phpjs.org/functions/var_export/
// original by: Philip Peterson
// improved by: johnrembo
// improved by: Brett Zamir (http://brett-zamir.me)
// input by: Brian Tafoya (http://www.premasolutions.com/)
// input by: Hans Henrik (http://hanshenrik.tk/)
// bugfixed by: Brett Zamir (http://brett-zamir.me)
// bugfixed by: Brett Zamir (http://brett-zamir.me)
// depends on: echo
// example 1: var_export(null);
// returns 1: null
// example 2: var_export({0: 'Kevin', 1: 'van', 2: 'Zonneveld'}, true);
// returns 2: "array (\n 0 => 'Kevin',\n 1 => 'van',\n 2 => 'Zonneveld'\n)"
// example 3: data = 'Kevin';
// example 3: var_export(data, true);
// returns 3: "'Kevin'"
var retstr = '',
iret = '',
value,
cnt = 0,
x = [],
i = 0,
funcParts = [],
// We use the last argument (not part of PHP) to pass in
// our indentation level
idtLevel = arguments[2] || 2,
innerIndent = '',
outerIndent = '',
getFuncName = function(fn) {
var name = (/\W*function\s+([\w\$]+)\s*\(/)
.exec(fn);
if (!name) {
return '(Anonymous)';
}
return name[1];
};
_makeIndent = function(idtLevel) {
return (new Array(idtLevel + 1))
.join(' ');
};
__getType = function(inp) {
var i = 0,
match, types, cons, type = typeof inp;
if (type === 'object' && (inp && inp.constructor) &&
getFuncName(inp.constructor) === 'PHPJS_Resource') {
return 'resource';
}
if (type === 'function') {
return 'function';
}
if (type === 'object' && !inp) {
// Should this be just null?
return 'null';
}
if (type === 'object') {
if (!inp.constructor) {
return 'object';
}
cons = inp.constructor.toString();
match = cons.match(/(\w+)\(/);
if (match) {
cons = match[1].toLowerCase();
}
types = ['boolean', 'number', 'string', 'array'];
for (i = 0; i < types.length; i++) {
if (cons === types[i]) {
type = types[i];
break;
}
}
}
return type;
};
type = __getType(mixed_expression);
if (type === null) {
retstr = 'NULL';
} else if (type === 'array' || type === 'object') {
outerIndent = _makeIndent(idtLevel - 2);
innerIndent = _makeIndent(idtLevel);
for (i in mixed_expression) {
value = this.var_export(mixed_expression[i], 1, idtLevel + 2);
value = typeof value === 'string' ? value.replace(/</g, '<')
.
replace(/>/g, '>'): value;
x[cnt++] = innerIndent + i + ' => ' +
(__getType(mixed_expression[i]) === 'array' ?
'\n' : '') + value;
}
iret = x.join(',\n');
retstr = outerIndent + 'array (\n' + iret + '\n' + outerIndent + ')';
} else if (type === 'function') {
funcParts = mixed_expression.toString()
.
match(/function .*?\((.*?)\) \{([\s\S]*)\}/);
// For lambda functions, var_export() outputs such as the following:
// '\000lambda_1'. Since it will probably not be a common use to
// expect this (unhelpful) form, we'll use another PHP-exportable
// construct, create_function() (though dollar signs must be on the
// variables in JavaScript); if using instead in JavaScript and you
// are using the namespaced version, note that create_function() will
// not be available as a global
retstr = "create_function ('" + funcParts[1] + "', '" +
funcParts[2].replace(new RegExp("'", 'g'), "\\'") + "')";
} else if (type === 'resource') {
// Resources treated as null for var_export
retstr = 'NULL';
} else {
retstr = typeof mixed_expression !== 'string' ? mixed_expression :
"'" + mixed_expression.replace(/(["'])/g, '\\$1')
.
replace(/\0/g, '\\0') + "'";
}
if (!bool_return) {
this.echo(retstr);
return null;
}
return retstr;
}
JavaScript中的echo()
http://phpjs.org/functions/echo/
function echo() {
// discuss at: http://phpjs.org/functions/echo/
// original by: Philip Peterson
// improved by: echo is bad
// improved by: Nate
// improved by: Brett Zamir (http://brett-zamir.me)
// improved by: Brett Zamir (http://brett-zamir.me)
// improved by: Brett Zamir (http://brett-zamir.me)
// revised by: Der Simon (http://innerdom.sourceforge.net/)
// bugfixed by: Eugene Bulkin (http://doubleaw.com/)
// bugfixed by: Brett Zamir (http://brett-zamir.me)
// bugfixed by: Brett Zamir (http://brett-zamir.me)
// bugfixed by: EdorFaus
// input by: JB
// note: If browsers start to support DOM Level 3 Load and Save (parsing/serializing),
// note: we wouldn't need any such long code (even most of the code below). See
// note: link below for a cross-browser implementation in JavaScript. HTML5 might
// note: possibly support DOMParser, but that is not presently a standard.
// note: Although innerHTML is widely used and may become standard as of HTML5, it is also not ideal for
// note: use with a temporary holder before appending to the DOM (as is our last resort below),
// note: since it may not work in an XML context
// note: Using innerHTML to directly add to the BODY is very dangerous because it will
// note: break all pre-existing references to HTMLElements.
// example 1: echo('<div><p>abc</p><p>abc</p></div>');
// returns 1: undefined
var isNode = typeof module !== 'undefined' && module.exports && typeof global !== "undefined" && {}.toString.call(
global) == '[object global]';
if (isNode) {
var args = Array.prototype.slice.call(arguments);
return console.log(args.join(' '));
}
var arg = '';
var argc = arguments.length;
var argv = arguments;
var i = 0;
var holder, win = this.window;
var d = win.document;
var ns_xhtml = 'http://www.w3.org/1999/xhtml';
// If we're in a XUL context
var ns_xul = 'http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul';
var stringToDOM = function(str, parent, ns, container) {
var extraNSs = '';
if (ns === ns_xul) {
extraNSs = ' xmlns:html="' + ns_xhtml + '"';
}
var stringContainer = '<' + container + ' xmlns="' + ns + '"' + extraNSs + '>' + str + '</' + container + '>';
var dils = win.DOMImplementationLS;
var dp = win.DOMParser;
var ax = win.ActiveXObject;
if (dils && dils.createLSInput && dils.createLSParser) {
// Follows the DOM 3 Load and Save standard, but not
// implemented in browsers at present; HTML5 is to standardize on innerHTML, but not for XML (though
// possibly will also standardize with DOMParser); in the meantime, to ensure fullest browser support, could
// attach http://svn2.assembla.com/svn/brettz9/DOMToString/DOM3.js (see http://svn2.assembla.com/svn/brettz9/DOMToString/DOM3.xhtml for a simple test file)
var lsInput = dils.createLSInput();
// If we're in XHTML, we'll try to allow the XHTML namespace to be available by default
lsInput.stringData = stringContainer;
// synchronous, no schema type
var lsParser = dils.createLSParser(1, null);
return lsParser.parse(lsInput)
.firstChild;
} else if (dp) {
// If we're in XHTML, we'll try to allow the XHTML namespace to be available by default
try {
var fc = new dp()
.parseFromString(stringContainer, 'text/xml');
if (fc && fc.documentElement && fc.documentElement.localName !== 'parsererror' && fc.documentElement.namespaceURI !==
'http://www.mozilla.org/newlayout/xml/parsererror.xml') {
return fc.documentElement.firstChild;
}
// If there's a parsing error, we just continue on
} catch (e) {
// If there's a parsing error, we just continue on
}
} else if (ax) {
// We don't bother with a holder in Explorer as it doesn't support namespaces
var axo = new ax('MSXML2.DOMDocument');
axo.loadXML(str);
return axo.documentElement;
}
/*else if (win.XMLHttpRequest) {
// Supposed to work in older Safari
var req = new win.XMLHttpRequest;
req.open('GET', 'data:application/xml;charset=utf-8,'+encodeURIComponent(str), false);
if (req.overrideMimeType) {
req.overrideMimeType('application/xml');
}
req.send(null);
return req.responseXML;
}*/
// Document fragment did not work with innerHTML, so we create a temporary element holder
// If we're in XHTML, we'll try to allow the XHTML namespace to be available by default
//if (d.createElementNS && (d.contentType && d.contentType !== 'text/html')) {
// Don't create namespaced elements if we're being served as HTML (currently only Mozilla supports this detection in true XHTML-supporting browsers, but Safari and Opera should work with the above DOMParser anyways, and IE doesn't support createElementNS anyways)
if (d.createElementNS && // Browser supports the method
(d.documentElement.namespaceURI || // We can use if the document is using a namespace
d.documentElement.nodeName.toLowerCase() !== 'html' || // We know it's not HTML4 or less, if the tag is not HTML (even if the root namespace is null)
(d.contentType && d.contentType !== 'text/html') // We know it's not regular HTML4 or less if this is Mozilla (only browser supporting the attribute) and the content type is something other than text/html; other HTML5 roots (like svg) still have a namespace
)) {
// Don't create namespaced elements if we're being served as HTML (currently only Mozilla supports this detection in true XHTML-supporting browsers, but Safari and Opera should work with the above DOMParser anyways, and IE doesn't support createElementNS anyways); last test is for the sake of being in a pure XML document
holder = d.createElementNS(ns, container);
} else {
// Document fragment did not work with innerHTML
holder = d.createElement(container);
}
holder.innerHTML = str;
while (holder.firstChild) {
parent.appendChild(holder.firstChild);
}
return false;
// throw 'Your browser does not support DOM parsing as required by echo()';
};
var ieFix = function(node) {
if (node.nodeType === 1) {
var newNode = d.createElement(node.nodeName);
var i, len;
if (node.attributes && node.attributes.length > 0) {
for (i = 0, len = node.attributes.length; i < len; i++) {
newNode.setAttribute(node.attributes[i].nodeName, node.getAttribute(node.attributes[i].nodeName));
}
}
if (node.childNodes && node.childNodes.length > 0) {
for (i = 0, len = node.childNodes.length; i < len; i++) {
newNode.appendChild(ieFix(node.childNodes[i]));
}
}
return newNode;
} else {
return d.createTextNode(node.nodeValue);
}
};
var replacer = function(s, m1, m2) {
// We assume for now that embedded variables do not have dollar sign; to add a dollar sign, you currently must use {$$var} (We might change this, however.)
// Doesn't cover all cases yet: see http://php.net/manual/en/language.types.string.php#language.types.string.syntax.double
if (m1 !== '\\') {
return m1 + eval(m2);
} else {
return s;
}
};
this.php_js = this.php_js || {};
var phpjs = this.php_js;
var ini = phpjs.ini;
var obs = phpjs.obs;
for (i = 0; i < argc; i++) {
arg = argv[i];
if (ini && ini['phpjs.echo_embedded_vars']) {
arg = arg.replace(/(.?)\{?\$(\w*?\}|\w*)/g, replacer);
}
if (!phpjs.flushing && obs && obs.length) {
// If flushing we output, but otherwise presence of a buffer means caching output
obs[obs.length - 1].buffer += arg;
continue;
}
if (d.appendChild) {
if (d.body) {
if (win.navigator.appName === 'Microsoft Internet Explorer') {
// We unfortunately cannot use feature detection, since this is an IE bug with cloneNode nodes being appended
d.body.appendChild(stringToDOM(ieFix(arg)));
} else {
var unappendedLeft = stringToDOM(arg, d.body, ns_xhtml, 'div')
.cloneNode(true); // We will not actually append the div tag (just using for providing XHTML namespace by default)
if (unappendedLeft) {
d.body.appendChild(unappendedLeft);
}
}
} else {
// We will not actually append the description tag (just using for providing XUL namespace by default)
d.documentElement.appendChild(stringToDOM(arg, d.documentElement, ns_xul, 'description'));
}
} else if (d.write) {
d.write(arg);
} else {
console.log(arg);
}
}
}
我提出这一点是为了帮助那些需要实用的东西的人，给你一个漂亮的、美化的(缩进的)JS节点的图片。对于节点，没有其他解决方案适合我(“周期性错误”或其他什么…)。这将引导您遍历DOM Node下的树(不使用递归)，并为您提供深度、tagName(如果适用)和textContent(如果适用)。
在头节点下走过树时遇到的任何其他节点细节都可以根据自己的兴趣添加……
function printRNode( node ){
// make sort of human-readable picture of the node... a bit like PHP print_r
if( node === undefined || node === null ){
throwError( 'node was ' + typeof node );
}
let s = '';
// NB walkDOM could be made into a utility function which you could
// call with one or more callback functions as parameters...
function walkDOM( headNode ){
const stack = [ headNode ];
const depthCountDowns = [ 1 ];
while (stack.length > 0) {
const node = stack.pop();
const depth = depthCountDowns.length - 1;
// TODO non-text, non-BR nodes could show more details (attributes, properties, etc.)
const stringRep = node.nodeType === 3? 'TEXT: |' + node.nodeValue + '|' : 'tag: ' + node.tagName;
s += ' '.repeat( depth ) + stringRep + '\n';
const lastIndex = depthCountDowns.length - 1;
depthCountDowns[ lastIndex ] = depthCountDowns[ lastIndex ] - 1;
if( node.childNodes.length ){
depthCountDowns.push( node.childNodes.length );
stack.push( ... Array.from( node.childNodes ).reverse() );
}
while( depthCountDowns[ depthCountDowns.length - 1 ] === 0 ){
depthCountDowns.splice( -1 );
}
}
}
walkDOM( node );
return s;
}
