我写了这个JS函数dump()来像PHP的var_dump()一样工作。 要在警报窗口中显示变量的内容:dump(variable) 要在网页中显示变量的内容:dump(variable， 'body') 获取变量的字符串:dump(variable， 'none')

/* repeatString() returns a string which has been repeated a set number of times */
function repeatString(str, num) {
    out = '';
    for (var i = 0; i < num; i++) {
        out += str;
    }
    return out;
}

/*
dump() displays the contents of a variable like var_dump() does in PHP. dump() is
better than typeof, because it can distinguish between array, null and object.
Parameters:
    v:              The variable
    howDisplay:     "none", "body", "alert" (default)
    recursionLevel: Number of times the function has recursed when entering nested
                    objects or arrays. Each level of recursion adds extra space to the
                    output to indicate level. Set to 0 by default.
Return Value:
    A string of the variable's contents
Limitations:
    Can't pass an undefined variable to dump(). 
    dump() can't distinguish between int and float.
    dump() can't tell the original variable type of a member variable of an object.
    These limitations can't be fixed because these are *features* of JS. However, dump()
*/
function dump(v, howDisplay, recursionLevel) {
    howDisplay = (typeof howDisplay === 'undefined') ? "alert" : howDisplay;
    recursionLevel = (typeof recursionLevel !== 'number') ? 0 : recursionLevel;

    var vType = typeof v;
    var out = vType;

    switch (vType) {
        case "number":
        /* there is absolutely no way in JS to distinguish 2 from 2.0
           so 'number' is the best that you can do. The following doesn't work:
           var er = /^[0-9]+$/;
           if (!isNaN(v) && v % 1 === 0 && er.test(3.0)) {
               out = 'int';
           }
        */
        break;
    case "boolean":
        out += ": " + v;
        break;
    case "string":
        out += "(" + v.length + '): "' + v + '"';
        break;
    case "object":
        //check if null
        if (v === null) {
            out = "null";
        }
        //If using jQuery: if ($.isArray(v))
        //If using IE: if (isArray(v))
        //this should work for all browsers according to the ECMAScript standard:
        else if (Object.prototype.toString.call(v) === '[object Array]') {
            out = 'array(' + v.length + '): {\n';
            for (var i = 0; i < v.length; i++) {
                out += repeatString('   ', recursionLevel) + "   [" + i + "]:  " +
                    dump(v[i], "none", recursionLevel + 1) + "\n";
            }
            out += repeatString('   ', recursionLevel) + "}";
        }
        else {
            //if object
            let sContents = "{\n";
            let cnt = 0;
            for (var member in v) {
                //No way to know the original data type of member, since JS
                //always converts it to a string and no other way to parse objects.
                sContents += repeatString('   ', recursionLevel) + "   " + member +
                    ":  " + dump(v[member], "none", recursionLevel + 1) + "\n";
                cnt++;
            }
            sContents += repeatString('   ', recursionLevel) + "}";
            out += "(" + cnt + "): " + sContents;
        }
        break;
    default:
        out = v;
        break;
    }

    if (howDisplay == 'body') {
        var pre = document.createElement('pre');
        pre.innerHTML = out;
        document.body.appendChild(pre);
    }
    else if (howDisplay == 'alert') {
        alert(out);
    }

    return out;
}

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

最常见的方式:

console.log(object);

但是我必须提到JSON。Stringify用于转储非浏览器脚本中的变量:

console.log( JSON.stringify(object) );

JSON。正如Simon Zyx指出的那样，stringify函数还支持内置的修饰。

例子:

var obj = {x: 1, y: 2, z: 3};

console.log( JSON.stringify(obj, null, 2) ); // spacing level = 2

上面的代码片段将打印:

{
  "x": 1,
  "y": 2,
  "z": 3
}

在caniuse.com上，您可以查看原生支持JSON的浏览器。Stringify函数:http://caniuse.com/json

您还可以使用Douglas Crockford库来添加JSON。旧浏览器上的stringify支持:https://github.com/douglascrockford/JSON-js

JSON文档。stringify: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify

我希望这对你有帮助:-)

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。

将JSON响应解析为HTML的一个很好的简单解决方案。

var json_response = jQuery.parseJSON(data);
html_response += 'JSON Response:<br />';

jQuery.each(json_response, function(k, v) {
    html_response += outputJSONReponse(k, v);
});

function outputJSONReponse(k, v) {
    var html_response = k + ': ';

    if(jQuery.isArray(v) || jQuery.isPlainObject(v)) {
        jQuery.each(v, function(j, w) {
            html_response += outputJSONReponse(j, w);
        });
    } else {
        html_response += v + '<br />';
    }

    return html_response;
}

你也可以试试这个函数。我不记得原作者了，但所有功劳都归他们。

工作就像一个魅力- 100%相同的var_dump在PHP。

来看看。

function dump(arr,level) { var dumped_text = ""; if(!level) level = 0; //The padding given at the beginning of the line. var level_padding = ""; for(var j=0;j<level+1;j++) level_padding += " "; if(typeof(arr) == 'object') { //Array/Hashes/Objects for(var item in arr) { var value = arr[item]; if(typeof(value) == 'object') { //If it is an array, dumped_text += level_padding + "'" + item + "' ...\n"; dumped_text += dump(value,level+1); } else { dumped_text += level_padding + "'" + item + "' => \"" + value + "\"\n"; } } } else { //Stings/Chars/Numbers etc. dumped_text = "===>"+arr+"<===("+typeof(arr)+")"; } return dumped_text; } // Example: var employees = [ { id: '1', sex: 'm', city: 'Paris' }, { id: '2', sex: 'f', city: 'London' }, { id: '3', sex: 'f', city: 'New York' }, { id: '4', sex: 'm', city: 'Moscow' }, { id: '5', sex: 'm', city: 'Berlin' } ] // Open dev console (F12) to see results: console.log(dump(employees));