javascript-在对象数组中搜索字符串

Question

我想在对象数组中搜索字符串并返回匹配的对象。 在这里尝试使用es6 。

请找到以下代码：

 // set of keys const defConfigs = [{ title: "Id", key: "id" }, { title: "Tenant", key: "tenant" }, { title: "Opened", key: "opened" }, { title: "Title", key: "title" }, { title: "Status", key: "status" }, { title: "Priority", key: "priority" } ]; // items as array of objects const items = [{ id: "INC000000004519", title: "Follow-up after INC000000004507", description: null, urgency: "4-Low", severity: "4-Minor/Localized" }, { id: "INC000000004515", title: "network drop:↵Network Element CVU042_Johnstown get unsynchronized↵Network Element CVU043_Redman", description: "Client network drop since 08:51 until 09:06, pleas…ork Element CVU045_North_Salem get unsynchronized", urgency: "3-Medium", severity: "3-Moderate/Limited" }, { id: "INC000000004088", title: "not able to schedule GPEH in ABC", description: "Contact: abc@xyz.com↵+14692669295↵…WCDMA, we are not able to schedule GPEH in ABC. I", urgency: "4-Low", severity: "4-Minor/Localized" }, { id: "INC000000004512", title: "SR Updated - P3 - 2018-0427-0305 - xyz TELECOMMUNICATIONS ROMANIA SRL - Lost the mng connect", description: null, urgency: "4-Low", severity: "4-Minor/Localized" }, { id: "INC000000004414", title: "Acme incident 1 title", description: "Acme incident 1 description", urgency: "2-High", severity: "1-Extensive/Widespread" } ]; // trying to search for string in keys defined in defConfigs items.filter(item => defConfigs.forEach((def) => { if (def.key in item) { return (item[def.key].toString().toLowerCase().match('low').length > 1); } })); // always throws an error Uncaught TypeError: Cannot read property 'length' of null console.log(items); 

在这里，有3个对象的字符串为“ low”，我希望代码返回第一项（其中“ title”为“ Fol low- up after”）； 但是match永远不会回来。

如何在对象数组中搜索字符串并作为结果返回这些对象？

Answer 1

如果没有匹配项， String.prototype.match()函数将返回null ，因此您需要检查这种情况。 接下来，您可以使用Array.prototype.some()函数来验证数组中的至少一项是否满足您的条件。 例如：

items.filter(item =>
  // check if at least one key from `defConfigs` on `item` matches 'low'
  defConfigs.some((def) => {
    if (def.key in item) {
      const matched = item[def.key].toString().toLowerCase().match('low')
      // return true if item matched
      return !!matched
   }
   // match not found by default
   return false
}));

Answer 2

如果仔细观察，您会注意到：

1. 您无需检查.match匹配（如果没有匹配，则返回null ；测试null.length将引发错误）
2. 您正在检查match.length > 1 ...您使用的语法将返回一个数组，该数组仅包含一项或null
3. 您缺少.filter的return语句
4. 您没有将.filter的返回值分配给任何变量

这是您需要做的：

var filteredItems = items.filter(function (item) {
    return defConfigs.some(function (def) {
        return (def.key in item)
            ? item[def.key].toString().toLowerCase().match('low') !== null
            : false;
    });
});
console.log(filteredItems);

Answer 3

如果找不到匹配项，则String.prototype.match（）将返回null。 如果您希望匹配结果工作，则应严格将匹配结果与null进行比较。

您应该看看Array.prototype.filter 。 它返回一个新数组，并且不会修改作为参数传递的引用，您的原始项目是安全的（现在）。

Answer 4

单词“低”只在紧迫属性中找到和你defConfigs阵列没有这个领域
因此，将其添加到数组后，请执行以下操作：

let newItems=items.filter(item => {


    let count= defConfigs.reduce((acc, def) => {

        if (def.key in item) {
            let arr = item[def.key].toString().toLowerCase().match(/low/gi)
            return acc + (arr ? 1 : 0);
        }
        else {

            return acc;
        }
    }, 0)

    return count >0
});

console.log(newItems);

• 因此，首先为过滤后的数据newItems定义一个新变量
• 然后我使用了reduce函数来获取整个对象是否匹配
• 最后在match函数中使用了正则表达式/ low / gi

Answer 5

在您的if语句中， if (def.key in item)将检查def.key的值是否等于item中的属性的名称。 要完成您想做的事情，请参见下面的代码中的注释：

// set of keys
const defConfigs = [{title: "Id", key: "id"},
{title: "Tenant", key: "tenant"},
{title: "Opened", key: "opened"},
{title: "Title", key: "title"},
{title: "Status", key: "status"},
{title: "Priority", key: "priority"}];

// items as array of objects
const items = [{id: "INC000000004519", title: "Follow-up after INC000000004507", description: null, urgency: "4-Low", severity: "4-Minor/Localized"},
{id: "INC000000004515", title: "network drop:↵Network Element CVU042_Johnstown get unsynchronized↵Network Element CVU043_Redman", description: "Client network drop since 08:51 until 09:06, pleas…ork Element CVU045_North_Salem get unsynchronized", urgency: "3-Medium", severity: "3-Moderate/Limited"},
{id: "INC000000004088", title: "not able to schedule GPEH in ABC", description: "Contact: abc@xyz.com↵+14692669295↵…WCDMA, we are not able to schedule GPEH in ABC. I", urgency: "4-Low", severity: "4-Minor/Localized"},
{id: "INC000000004512", title: "SR Updated - P3 - 2018-0427-0305 - xyz TELECOMMUNICATIONS ROMANIA S.R.L - Lost the  mng connect", description: null, urgency: "4-Low", severity: "4-Minor/Localized"},
{id: "INC000000004414", title: "Acme incident 1 title", description: "Acme incident 1 description", urgency: "2-High", severity: "1-Extensive/Widespread"}];


// trying to search for string in keys defined in defConfigs
items.filter(item =>
defConfigs.forEach((def) => {
  //iterate through all attributes in the object
  for(var key in item){
    //check if the attribute exists, if it has the method 'indexOf' (if it's a string), and that it has def.key in the string
    if (item[key] && item[key].indexOf && item[key].indexOf(def.key)!= -1) {
      //match only accepts regular expressions which are signified in JS by enclosing the expression with forward slashes
      return (item[def.key].toString().toLowerCase().match(/low/).length >1);
    }
   }
}));