problems installing gulp and pdf.js

Question

I'm following this and try to use pdf.js. I've downloaded and extracted the library and now I was trying to install gulp globally as it says on the page but when I run the command

C:\Users\xx\Desktop\pdfSearch2>npm install -g gulp-cli

I get errors:

npm ERR! Windows_NT 6.1.7601
npm ERR! argv "C:\\Program Files\\nodejs\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js" "install" "-g"
 "gulp-cli"
npm ERR! node v6.9.1
npm ERR! npm  v3.10.8
npm ERR! code UNABLE_TO_GET_ISSUER_CERT_LOCALLY

npm ERR! unable to get local issuer certificate
npm ERR!
npm ERR! If you need help, you may report this error at:
npm ERR!     <https://github.com/npm/npm/issues>

npm ERR! Please include the following file with any support request:
npm ERR!     C:\Users\xx\Desktop\pdfSearch2\npm-debug.log

And here is the full npm-debug.log:

0 info it worked if it ends with ok
1 verbose cli [ 'C:\\Program Files\\nodejs\\node.exe',
1 verbose cli   'C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js',
1 verbose cli   'install',
1 verbose cli   '-g',
1 verbose cli   'gulp-cli' ]
2 info using npm@3.10.8
3 info using node@v6.9.1
4 silly loadCurrentTree Starting
5 silly install loadCurrentTree
6 silly install readGlobalPackageData
7 silly fetchPackageMetaData gulp-cli
8 silly fetchNamedPackageData gulp-cli
9 silly mapToRegistry name gulp-cli
10 silly mapToRegistry using default registry
11 silly mapToRegistry registry https://registry.npmjs.org/
12 silly mapToRegistry data Result {
12 silly mapToRegistry   raw: 'gulp-cli',
12 silly mapToRegistry   scope: null,
12 silly mapToRegistry   escapedName: 'gulp-cli',
12 silly mapToRegistry   name: 'gulp-cli',
12 silly mapToRegistry   rawSpec: '',
12 silly mapToRegistry   spec: 'latest',
12 silly mapToRegistry   type: 'tag' }
13 silly mapToRegistry uri https://registry.npmjs.org/gulp-cli
14 verbose request uri https://registry.npmjs.org/gulp-cli
15 verbose request no auth needed
16 info attempt registry request try #1 at 8:39:43 AM
17 verbose request id d0dd4dbe0b1dc495
18 http request GET https://registry.npmjs.org/gulp-cli
19 info retry will retry, error on last attempt: Error: unable to get local issuer certificate
20 info attempt registry request try #2 at 8:39:53 AM
21 http request GET https://registry.npmjs.org/gulp-cli
22 info retry will retry, error on last attempt: Error: unable to get local issuer certificate
23 info attempt registry request try #3 at 8:40:53 AM
24 http request GET https://registry.npmjs.org/gulp-cli
25 silly fetchPackageMetaData Error: unable to get local issuer certificate
25 silly fetchPackageMetaData     at Error (native)
25 silly fetchPackageMetaData     at TLSSocket.<anonymous> (_tls_wrap.js:1062:38)
25 silly fetchPackageMetaData     at emitNone (events.js:86:13)
25 silly fetchPackageMetaData     at TLSSocket.emit (events.js:185:7)
25 silly fetchPackageMetaData     at TLSSocket._finishInit (_tls_wrap.js:586:8)
25 silly fetchPackageMetaData     at TLSWrap.ssl.onhandshakedone (_tls_wrap.js:416:38)
25 silly fetchPackageMetaData  error for gulp-cli { Error: unable to get local issuer certificate
25 silly fetchPackageMetaData     at Error (native)
25 silly fetchPackageMetaData     at TLSSocket.<anonymous> (_tls_wrap.js:1062:38)
25 silly fetchPackageMetaData     at emitNone (events.js:86:13)
25 silly fetchPackageMetaData     at TLSSocket.emit (events.js:185:7)
25 silly fetchPackageMetaData     at TLSSocket._finishInit (_tls_wrap.js:586:8)
25 silly fetchPackageMetaData     at TLSWrap.ssl.onhandshakedone (_tls_wrap.js:416:38) code: 'UNABLE_TO_GET_ISSUER_CERT_LOCALLY' }
26 silly rollbackFailedOptional Starting
27 silly rollbackFailedOptional Finishing
28 silly runTopLevelLifecycles Finishing
29 silly install printInstalled
30 verbose stack Error: unable to get local issuer certificate
30 verbose stack     at Error (native)
30 verbose stack     at TLSSocket.<anonymous> (_tls_wrap.js:1062:38)
30 verbose stack     at emitNone (events.js:86:13)
30 verbose stack     at TLSSocket.emit (events.js:185:7)
30 verbose stack     at TLSSocket._finishInit (_tls_wrap.js:586:8)
30 verbose stack     at TLSWrap.ssl.onhandshakedone (_tls_wrap.js:416:38)
31 verbose cwd C:\Users\xx\Desktop\pdfSearch2
32 error Windows_NT 6.1.7601
33 error argv "C:\\Program Files\\nodejs\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js" "install" "-g" "gulp-cli"
34 error node v6.9.1
35 error npm  v3.10.8
36 error code UNABLE_TO_GET_ISSUER_CERT_LOCALLY
37 error unable to get local issuer certificate
38 error If you need help, you may report this error at:
38 error     <https://github.com/npm/npm/issues>
39 verbose exit [ 1, true ]

Any idea what I'm doing wrong? thanks

EDIT: so running this C:\Users\antoniob\Desktop\pdfSearch2>npm config set strict-ssl=false has worked but now I don't seem to be able to install the pdf.js dependencies:

C:\Users\xx\Desktop\pdfSearch2>npm install
npm WARN enoent ENOENT: no such file or directory, open 'C:\Users\xx\Desktop\pdfSearch2\package.json'
npm WARN pdfSearch2 No description
npm WARN pdfSearch2 No repository field.
npm WARN pdfSearch2 No README data
npm WARN pdfSearch2 No license field.

Answer 1

I have faced thit issue recently, it can be caused by different reasons. But usually, it is firewall or proxy behind which is your network that cause this error.

My solution was npm config set strict-ssl=false command which cancels check of the SSL certificates by npm. But be warned that this solution is insecure, it is better to configure your firewall or proxy properly. So after packages installing run npm config set strict-ssl=true command.