如何以字符串格式显示JavaScript对象的内容,就像我们警告变量时一样?

与显示对象的格式相同。


当前回答

在控制台中显示对象的另一种方法是使用JSON.stringify。请查看以下示例:

var gandalf = {
  "real name": "Gandalf",
  "age (est)": 11000,
  "race": "Maia",
  "haveRetirementPlan": true,
  "aliases": [
    "Greyhame",
    "Stormcrow",
    "Mithrandir",
    "Gandalf the Grey",
    "Gandalf the White"
  ]
};
//to console log object, we cannot use console.log("Object gandalf: " + gandalf);
console.log("Object gandalf: ");
//this will show object gandalf ONLY in Google Chrome NOT in IE
console.log(gandalf);
//this will show object gandalf IN ALL BROWSERS!
console.log(JSON.stringify(gandalf));
//this will show object gandalf IN ALL BROWSERS! with beautiful indent
console.log(JSON.stringify(gandalf, null, 4));

其他回答

这是函数。

function printObj(obj) {
console.log((function traverse(tab, obj) {
    let str = "";
    if(typeof obj !== 'object') {
        return obj + ',';
    }
    if(Array.isArray(obj)) {            
        return '[' + obj.map(o=>JSON.stringify(o)).join(',') + ']' + ',';
    }
    str = str + '{\n';
    for(var p in obj) {
        str = str + tab + ' ' + p + ' : ' + traverse(tab+' ', obj[p]) +'\n';
    }
    str = str.slice(0,-2) + str.slice(-1);                
    str = str + tab + '},';
    return str;
}('',obj).slice(0,-1)))};

它可以使用具有可读性的制表符缩进来显示对象。

好吧,Firefox(感谢@Bojangles提供详细信息)有Object.toSource()方法,它将对象打印为JSON和function(){}。

我想,对于大多数调试目的来说,这已经足够了。

使用本机JSON.stringify方法。适用于嵌套对象,所有主要浏览器都支持此方法。

str = JSON.stringify(obj);
str = JSON.stringify(obj, null, 4); // (Optional) beautiful indented output.
console.log(str); // Logs output to dev tools console.
alert(str); // Displays output using window.alert()

链接到Mozilla API参考和其他示例。

obj = JSON.parse(str); // Reverses above operation (Just in case if needed.)

如果您遇到此Javascript错误

"Uncaught TypeError: Converting circular structure to JSON"

假设对象obj={0:'John',1:'Foo',2:'Bar'}

打印对象的内容

for (var i in obj){
    console.log(obj[i], i);
}

控制台输出(Chrome DevTools):

John 0
Foo 1
Bar 2

希望这有帮助!

pagewils代码的另一个修改。。。他不打印字符串以外的任何内容,并将数字和布尔字段留空,我修复了megaboss创建的函数内部第二种类型的拼写错误。

var print = function( o, maxLevel, level )
{
    if ( typeof level == "undefined" )
    {
        level = 0;
    }
    if ( typeof maxlevel == "undefined" )
    {
        maxLevel = 0;
    }

    var str = '';
    // Remove this if you don't want the pre tag, but make sure to remove
    // the close pre tag on the bottom as well
    if ( level == 0 )
    {
        str = '<pre>';   // can also be <pre>
    }

    var levelStr = '<br>';
    for ( var x = 0; x < level; x++ )
    {
        levelStr += '    ';   // all those spaces only work with <pre>
    }

    if ( maxLevel != 0 && level >= maxLevel )
    {
        str += levelStr + '...<br>';
        return str;
    }

    for ( var p in o )
    {
        switch(typeof o[p])
        {
          case 'string':
          case 'number':    // .tostring() gets automatically applied
          case 'boolean':   // ditto
            str += levelStr + p + ': ' + o[p] + ' <br>';
            break;

          case 'object':    // this is where we become recursive
          default:
            str += levelStr + p + ': [ <br>' + print( o[p], maxLevel, level + 1 ) + levelStr + ']</br>';
            break;
        }
    }

    // Remove this if you don't want the pre tag, but make sure to remove
    // the open pre tag on the top as well
    if ( level == 0 )
    {
        str += '</pre>';   // also can be </pre>
    }
    return str;
};