Question

这是我第一次使用javascript。我有以下字符串：

document.write(str)
[{"company":1,"number_employees":5},
{"company":4,"number_employees":25},
{"company":5,"number_employees":5},
{"company":2,"number_employees":5},
{"company":4,"number_employees":25}]

我需要转换这个字符串，以便根据number_employees总结它们，如下所示：

Three companies have number_employees=5 and two companies have number_employees=25

我目前正在努力将字符串转换为javascript对象。一旦我有了asscoiative数组，我就可以将它转换为map并计算number_employees。

s_obj = eval('({' + messageBody + '})');
var result = s_obj.reduce(function(map, obj) {
    map[obj.key] = obj.val;
    return map;
}, {});

这给了我以下错误：

VM181:1 Uncaught SyntaxError: Unexpected token ,
at onMessage ((index):41)
at WebSocket.<anonymous> (stomp.min.js:8)

非常感谢任何帮助/提示/指导！

Answer 1

对您的数据做一些假设，您可以尝试这样的事情：

首先，使用JSON对象将JSON字符串转换为Object，然后在尝试使用Array.prototype.reduce进行汇总时（您将参数反转）

＆＃13;

var summary = {};
var messageBody = '[{"company":1,"number_employees":5},{"company":4,"number_employees":25},{"company":5,"number_employees":5},{"company":2,"number_employees":5},{"company":4,"number_employees":25}]';

JSON.parse(messageBody).reduce( (acc, cur) => {
    acc[cur.number_employees] = (acc[cur.number_employees] || 0) + 1;
    return acc;
}, summary);
for(entry of Object.keys(summary)) {
    if (summary.hasOwnProperty(entry)) {
        console.log(`There are ${summary[entry]} companies with ${entry} employees`);
    }
}

＆＃13;

Javascript - 将字符串转换为关联数组并按值汇总

1 个答案: