如何将带有数组的字符串转换为数组[重复]

Posted 2023-02-22

【中文标题】如何将带有数组的字符串转换为数组[重复]

【英文标题】：How to convert a string with arrays to an array [duplicate]

【发布时间】：2018-12-26 01:59:47

【问题描述】：

如何将这段响应转换为有效数组？ 我想对数据执行 Object.map：

var user_roles = "['store_owner', 'super_admin']";

这不是一个有效的 JSON，所以我不能使用 JSON.parse

【问题讨论】：

你如何产生这个字符串？也许JSON 兼容的字符串会更容易解析。

虽然这个字符串不能被JSON解析，它是有效的JS。也许你可以使用eval？

对，eval 有效，但这是一种解决方法。最好生成一个没有自定义格式的字符串。

这不是该问题的重复，因为它不是有效的 JSON

【参考方案1】：

我使用了 JSON.parse 的 polyfill 我找到了 here

并且将字符串的含义替换为由''单引号表示：

/*
    json_parse.js
    2016-05-02
    Public Domain.
    NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.
    This file creates a json_parse function.
        json_parse(text, reviver)
            This method parses a JSON text to produce an object or array.
            It can throw a SyntaxError exception.
            The optional reviver parameter is a function that can filter and
            transform the results. It receives each of the keys and values,
            and its return value is used instead of the original value.
            If it returns what it received, then the structure is not modified.
            If it returns undefined then the member is deleted.
            Example:
            // Parse the text. Values that look like ISO date strings will
            // be converted to Date objects.
            myData = json_parse(text, function (key, value) 
                var a;
                if (typeof value === "string") 
                    a =
/^(\d4)-(\d2)-(\d2)T(\d2):(\d2):(\d2(?:\.\d*)?)Z$/.exec(value);
                    if (a) 
                        return new Date(Date.UTC(+a[1], +a[2] - 1, +a[3], +a[4],
                            +a[5], +a[6]));
                    
                
                return value;
            );
    This is a reference implementation. You are free to copy, modify, or
    redistribute.
    This code should be minified before deployment.
    See http://javascript.crockford.com/jsmin.html
    USE YOUR OWN COPY. IT IS EXTREMELY UNWISE TO LOAD CODE FROM SERVERS YOU DO
    NOT CONTROL.
*/

/*jslint for */

/*property
    at, b, call, charAt, f, fromCharCode, hasOwnProperty, message, n, name,
    prototype, push, r, t, text
*/

var json_parse = (function () 
    "use strict";

// This is a function that can parse a JSON text, producing a JavaScript
// data structure. It is a simple, recursive descent parser. It does not use
// eval or regular expressions, so it can be used as a model for implementing
// a JSON parser in other languages.

// We are defining the function inside of another function to avoid creating
// global variables.

    var at;     // The index of the current character
    var ch;     // The current character
    var escapee = 
        "\"": "\"",
        "\\": "\\",
        "/": "/",
        b: "\b",
        f: "\f",
        n: "\n",
        r: "\r",
        t: "\t"
    ;
    var text;

    var error = function (m) 

// Call error when something is wrong.

        throw 
            name: "SyntaxError",
            message: m,
            at: at,
            text: text
        ;
    ;

    var next = function (c) 

// If a c parameter is provided, verify that it matches the current character.

        if (c && c !== ch) 
            error("Expected '" + c + "' instead of '" + ch + "'");
        

// Get the next character. When there are no more characters,
// return the empty string.

        ch = text.charAt(at);
        at += 1;
        return ch;
    ;

    var number = function () 

// Parse a number value.

        var value;
        var string = "";

        if (ch === "-") 
            string = "-";
            next("-");
        
        while (ch >= "0" && ch <= "9") 
            string += ch;
            next();
        
        if (ch === ".") 
            string += ".";
            while (next() && ch >= "0" && ch <= "9") 
                string += ch;
            
        
        if (ch === "e" || ch === "E") 
            string += ch;
            next();
            if (ch === "-" || ch === "+") 
                string += ch;
                next();
            
            while (ch >= "0" && ch <= "9") 
                string += ch;
                next();
            
        
        value = +string;
        if (!isFinite(value)) 
            error("Bad number");
         else 
            return value;
        
    ;

    var string = function () 

// Parse a string value.

        var hex;
        var i;
        var value = "";
        var uffff;

// When parsing for string values, we must look for " and \ characters.

        if (ch === "\'") 
            while (next()) 
                if (ch === "\'") 
                    next();
                    return value;
                
                if (ch === "\\") 
                    next();
                    if (ch === "u") 
                        uffff = 0;
                        for (i = 0; i < 4; i += 1) 
                            hex = parseInt(next(), 16);
                            if (!isFinite(hex)) 
                                break;
                            
                            uffff = uffff * 16 + hex;
                        
                        value += String.fromCharCode(uffff);
                     else if (typeof escapee[ch] === "string") 
                        value += escapee[ch];
                     else 
                        break;
                    
                 else 
                    value += ch;
                
            
        
        error("Bad string");
    ;

    var white = function () 

// Skip whitespace.

        while (ch && ch <= " ") 
            next();
        
    ;

    var word = function () 

// true, false, or null.

        switch (ch) 
        case "t":
            next("t");
            next("r");
            next("u");
            next("e");
            return true;
        case "f":
            next("f");
            next("a");
            next("l");
            next("s");
            next("e");
            return false;
        case "n":
            next("n");
            next("u");
            next("l");
            next("l");
            return null;
        
        error("Unexpected '" + ch + "'");
    ;

    var value;  // Place holder for the value function.

    var array = function () 

// Parse an array value.

        var arr = [];

        if (ch === "[") 
            next("[");
            white();
            if (ch === "]") 
                next("]");
                return arr;   // empty array
            
            while (ch) 
                arr.push(value());
                white();
                if (ch === "]") 
                    next("]");
                    return arr;
                
                next(",");
                white();
            
        
        error("Bad array");
    ;

    var object = function () 

// Parse an object value.

        var key;
        var obj = ;

        if (ch === "") 
            next("");
            white();
            if (ch === "") 
                next("");
                return obj;   // empty object
            
            while (ch) 
                key = string();
                white();
                next(":");
                if (Object.hasOwnProperty.call(obj, key)) 
                    error("Duplicate key '" + key + "'");
                
                obj[key] = value();
                white();
                if (ch === "") 
                    next("");
                    return obj;
                
                next(",");
                white();
            
        
        error("Bad object");
    ;

    value = function () 

// Parse a JSON value. It could be an object, an array, a string, a number,
// or a word.

        white();
        switch (ch) 
        case "":
            return object();
        case "[":
            return array();
        case "\'":
            return string();
        case "-":
            return number();
        default:
            return (ch >= "0" && ch <= "9")
                ? number()
                : word();
        
    ;

// Return the json_parse function. It will have access to all of the above
// functions and variables.

    return function (source, reviver) 
        var result;

        text = source;
        at = 0;
        ch = " ";
        result = value();
        white();
        if (ch) 
            error("Syntax error");
        

// If there is a reviver function, we recursively walk the new structure,
// passing each name/value pair to the reviver function for possible
// transformation, starting with a temporary root object that holds the result
// in an empty key. If there is not a reviver function, we simply return the
// result.

        return (typeof reviver === "function")
            ? (function walk(holder, key) 
                var k;
                var v;
                var val = holder[key];
                if (val && typeof val === "object") 
                    for (k in val) 
                        if (Object.prototype.hasOwnProperty.call(val, k)) 
                            v = walk(val, k);
                            if (v !== undefined) 
                                val[k] = v;
                             else 
                                delete val[k];
                            
                        
                    
                
                return reviver.call(holder, key, val);
            ("": result, ""))
            : result;
    ;
());

console.log(json_parse("['store_owner', 'super_admin']"));

【参考方案2】：

是的，这里发布的大多数答案都建议使用JSON.parse，然后在被删除之前被否决 3 次。人们在这里忽略的是缺少符合 JSON 标准的报价。但是，字符串是有效的 JavaScript。您可以执行以下操作：

const obj = 
  thing: "['store_owner', 'super_admin']",
  otherThing: "['apple', 'cookies']"


for (const key in obj) 
  const value = obj[key];
  obj[key] = eval(value);


console.log(obj);

输出将是一个有效的 javascript 对象：

"thing":["store_owner","super_admin"],"otherThing":["apple","cookies"] 

不过要小心eval()！ javascript eval() and security

你可以在这里试试：https://es6console.com/jjqvrnhg/

【讨论】：

Why is using the JavaScript eval function a bad idea?

@ZakariaAcharki 是的，是的...您只是在给已经提到的安全问题添加噪音（Berry 链接了一个类似的问题）...替代解决方案会更有用。

即使有警告eval() 也不应该被考虑。 OP 描述为“响应的一部分”的输入显然超出了他们的控制。这些警告特别适用于这种情况。

只要字符串不包含任何转义的单引号，它就可以工作："['store_owner', 'super_admin\'s right']"

我同意，@MarkMeyer。在这种情况下，最好的解决方案当然是重新考虑导致这种情况的整个设置。你永远不会像纪尧姆那样涵盖所有边缘情况。

【参考方案3】：

使其符合 JSON 标准

JSON.parse(user_roles.replace(/(?<!\\)'/g,'"')

这可以解决您的代码无法被 JSON 解析的原因。原因是 JSON 不允许您使用 单引号 (')，因此我们将它们更改为 双引号 (")

编辑：

我这样做是为了当 ' 前面有 \ 时，它不会被 " 替换。

【讨论】：

str = "['store_owner', 'super_ad\'min']", JSON.parse(str.replace(/'/g,'"')) => unexpected token m

这似乎不是 OP 可能遇到的问题，但我已经做到了，所以在这种情况下，它仍然可以工作。

我仍然得到完全相同的错误

@Adelin 它必须在字符串中以\ 开头，只需放置\' 返回' 你需要\\'

我认为这是迄今为止最好的解决方案......