admin管理员组

文章数量:1391995

I'm new to Node JS and am trying to set up a basic application that fetches my inbox (outlook) contents in JSON format. I tried using match function to filter the data based on subject but I keep getting this error - 

TypeError: Cannot read property 'match' of null
    at WriteStream.<anonymous> (C:\Users\52025088\Desktop\EMAIL APPROVAL DEMO\Outlook NODE\OFFICE365_NJS_DEMO.js:44:29)
    at Object.onceWrapper (events.js:273:13)
    at WriteStream.emit (events.js:182:13)
    at lazyFs.open (internal/fs/streams.js:278:10)
    at FSReqWrap.onplete (fs.js:141:20)

I tried using other string functions as well but keep getting similar errors.

I am able to print 'json.value[i].Subject' in console but cannot use it in match function.

/Request portion/

request(options, function(err, res, body) {  
let json = JSON.parse(body);

console.log(err);

var fileName = 'abc.html';
var html = '';
var stream = fs.createWriteStream(fileName);


stream.once('open', function(fd) {
for (var i = 0; i < json.value.length-1; i++){





        if(json.value[i].Subject.match(/Action Required/)){

            var dom = new JSDOM(json.value[i].Body.Content);

            console.log(json.value[i].Subject);

            html = html + '<br/>' + json.value[i].Subject + '<a href=' + dom.window.document.querySelector("a") + 'target="_top">Approve</a><br/><br/>';

        }       
}
html = '<!DOCTYPE html>'
   + '<html><head>' + "List Of Pending Items" + '</head><body>' + html + '</body></html>';
stream.end(html);
});

});

C:\Users\52025088\Desktop\EMAIL APPROVAL DEMO\Outlook NODE>node OFFICE365_NJS_DEMO.js
null
FW: Action Required: Approval of Earned Leave Absence Request for Vishnu Babu from 2019-03-26 to 2019-03-26
FW: Action Required: Approval of Earned Leave Absence Request for Vishnu Babu from 2019-05-08 to 2019-05-08
C:\Users\52025088\Desktop\EMAIL APPROVAL DEMO\Outlook NODE\OFFICE365_NJS_DEMO.js:44
                        if(json.value[i].Subject.match(/Action Required/)){
                                                 ^

TypeError: Cannot read property 'match' of null
    at WriteStream.<anonymous> (C:\Users\52025088\Desktop\EMAIL APPROVAL DEMO\Outlook NODE\OFFICE365_NJS_DEMO.js:44:29)
    at Object.onceWrapper (events.js:273:13)
    at WriteStream.emit (events.js:182:13)
    at lazyFs.open (internal/fs/streams.js:278:10)
    at FSReqWrap.onplete (fs.js:141:20)

I expect the match function to work so that I can filter based on Subject (json.value[i].Subject) but I guess I missed out something.

However I am able to get results if I hard code some string to pare with the Subject.

if(json.value[i].Subject == 'FW: Action Required: Approval of Earned Leave Absence Request for Vishnu Babu from 2019-03-26 to 2019-03-26'){

                var dom = new JSDOM(json.value[i].Body.Content);

                console.log(json.value[i].Subject);

                html = html + '<br/>' + json.value[i].Subject + '<a href=' + dom.window.document.querySelector("a") + 'target="_top">Approve</a><br/><br/>';

            }

C:\Users\52025088\Desktop\EMAIL APPROVAL DEMO\Outlook NODE>node OFFICE365_NJS_DEMO.js
null
FW: Action Required: Approval of Earned Leave Absence Request for Vishnu Babu from 2019-03-26 to 2019-03-26

I'm new to Node JS and am trying to set up a basic application that fetches my inbox (outlook) contents in JSON format. I tried using match function to filter the data based on subject but I keep getting this error - 

TypeError: Cannot read property 'match' of null
    at WriteStream.<anonymous> (C:\Users\52025088\Desktop\EMAIL APPROVAL DEMO\Outlook NODE\OFFICE365_NJS_DEMO.js:44:29)
    at Object.onceWrapper (events.js:273:13)
    at WriteStream.emit (events.js:182:13)
    at lazyFs.open (internal/fs/streams.js:278:10)
    at FSReqWrap.onplete (fs.js:141:20)

I tried using other string functions as well but keep getting similar errors.

I am able to print 'json.value[i].Subject' in console but cannot use it in match function.

/Request portion/

request(options, function(err, res, body) {  
let json = JSON.parse(body);

console.log(err);

var fileName = 'abc.html';
var html = '';
var stream = fs.createWriteStream(fileName);


stream.once('open', function(fd) {
for (var i = 0; i < json.value.length-1; i++){





        if(json.value[i].Subject.match(/Action Required/)){

            var dom = new JSDOM(json.value[i].Body.Content);

            console.log(json.value[i].Subject);

            html = html + '<br/>' + json.value[i].Subject + '<a href=' + dom.window.document.querySelector("a") + 'target="_top">Approve</a><br/><br/>';

        }       
}
html = '<!DOCTYPE html>'
   + '<html><head>' + "List Of Pending Items" + '</head><body>' + html + '</body></html>';
stream.end(html);
});

});

C:\Users\52025088\Desktop\EMAIL APPROVAL DEMO\Outlook NODE>node OFFICE365_NJS_DEMO.js
null
FW: Action Required: Approval of Earned Leave Absence Request for Vishnu Babu from 2019-03-26 to 2019-03-26
FW: Action Required: Approval of Earned Leave Absence Request for Vishnu Babu from 2019-05-08 to 2019-05-08
C:\Users\52025088\Desktop\EMAIL APPROVAL DEMO\Outlook NODE\OFFICE365_NJS_DEMO.js:44
                        if(json.value[i].Subject.match(/Action Required/)){
                                                 ^

TypeError: Cannot read property 'match' of null
    at WriteStream.<anonymous> (C:\Users\52025088\Desktop\EMAIL APPROVAL DEMO\Outlook NODE\OFFICE365_NJS_DEMO.js:44:29)
    at Object.onceWrapper (events.js:273:13)
    at WriteStream.emit (events.js:182:13)
    at lazyFs.open (internal/fs/streams.js:278:10)
    at FSReqWrap.onplete (fs.js:141:20)

I expect the match function to work so that I can filter based on Subject (json.value[i].Subject) but I guess I missed out something.

However I am able to get results if I hard code some string to pare with the Subject.

if(json.value[i].Subject == 'FW: Action Required: Approval of Earned Leave Absence Request for Vishnu Babu from 2019-03-26 to 2019-03-26'){

                var dom = new JSDOM(json.value[i].Body.Content);

                console.log(json.value[i].Subject);

                html = html + '<br/>' + json.value[i].Subject + '<a href=' + dom.window.document.querySelector("a") + 'target="_top">Approve</a><br/><br/>';

            }

C:\Users\52025088\Desktop\EMAIL APPROVAL DEMO\Outlook NODE>node OFFICE365_NJS_DEMO.js
null
FW: Action Required: Approval of Earned Leave Absence Request for Vishnu Babu from 2019-03-26 to 2019-03-26
  • javascript
  • node.js
  • json
  • string
Share Improve this question edited Jan 10, 2019 at 8:29 Anand Vegaraju asked Jan 10, 2019 at 8:11 Anand VegarajuAnand Vegaraju 271 gold badge1 silver badge7 bronze badges 5
  • We can't help you without an example of the JSON. From the error, clearly json_value[i].Subject is null, but we can't tell you why without the JSON. – T.J. Crowder Commented Jan 10, 2019 at 8:15
  • "I tried using other string functions as well but keep getting similar errors." because you are not operating on a string but undefined. That's what the error message is telling you when you do json.value[i].Subject.match() the json.value[i].Subject part evaluates to undefined, which doesn't have a .match() method. Examine your data and see if .Subject is the correct property to use. Note that it's case sensitive. – VLAZ Commented Jan 10, 2019 at 8:15
  • Thanks for your replies. The JSON is quite large. I am able to print json.value[i].Subject on console. – Anand Vegaraju Commented Jan 10, 2019 at 8:17
  • The JSON may be large, but it's entirely possible to show us its structure and/or a trimmed-down version of it. See: minimal reproducible example – T.J. Crowder Commented Jan 10, 2019 at 8:25
  • Hi TJ. I am able to run if I use a relational operator (==) to pare 'Subject' with a hard coded String (Updated the question). Thanks for your response. – Anand Vegaraju Commented Jan 10, 2019 at 8:31
Add a ment  | 

1 Answer 1

Reset to default 3

Change your if in:

const subject = json.value[i].Subject; // to make it shorter

if(subject && subject.match(/Action Required/)) {
  // your code
}

Using this if condition you'll use .match() function only if json.value[i].Subject is defined.

本文标签： nodejsHow to fix quotCannot read property 39match39 of undefinedquot error in JavaScriptStack Overflow

版权声明：本文标题：node.js - How to fix &quot;Cannot read property &#39;match&#39; of undefined&quot; error in JavaScript? - Stack 内容由网友自发贡献，该文观点仅代表作者本人， 转载请联系作者并注明出处：http://www.betaflare.com/web/1744586683a2614238.html， 本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌抄袭侵权/违法违规的内容，一经查实，本站将立刻删除。