The function I uses of bootstrap navbar dropdown doesn't work. My html code
It runs correctly on plunker. But when I run the same code. My running page becomes as follow:

When I click the Dropdown link, browser direct to "example.com"
This is my dependencies:
"@angular/common": "~4.0.0",
"@angular/compiler": "~4.0.0",
"@angular/core": "~4.0.0",
"@angular/forms": "~4.0.0",
"@angular/http": "~4.0.0",
"@angular/platform-browser": "~4.0.0",
"@angular/platform-browser-dynamic": "~4.0.0",
"@angular/router": "~4.0.0",
"angular-in-memory-web-api": "~0.3.0",
"systemjs": "0.19.40",
"core-js": "^2.4.1",
"rxjs": "5.0.1",
"zone.js": "^0.8.4"
Can anyone can help me to figure it out? Thank you!
href="http://example.com"link or change it to#.