angular2 how to change the default prefix of component to stop tslint warnings

You need to modify two files tslint.json and .angular-cli.json, suppose you want to change to myprefix:

In the tslint.json file just modify the following 2 attributes:

"directive-selector": [true, "attribute", "app", "camelCase"],
"component-selector": [true, "element", "app", "kebab-case"],

change "app" to "myprefix"

"directive-selector": [true, "attribute", "myprefix", "camelCase"],
"component-selector": [true, "element", "myprefix", "kebab-case"],

In the angular.json file just modify the attribute prefix: (For angular version less than 6, the file name is .angular-cli.json)

"app": [
  ...
  "prefix": "app",
  ...

change "app" to "myprefix"

"app": [
  ...
  "prefix": "myprefix",
  ...

If in the case you need more than one prefix as @Salil Junior point out:

"component-selector": [true, "element", ["myprefix1", "myprefix2"], "kebab-case"],

If creating a new project using Angular cli use this command line option

ng new project-name --prefix myprefix

For angular 6/7 onwards there will be a tslint.json inside your /src folder which holds the tslist rules for your component and directives.

{
    "extends": "../tslint.json",
    "rules": {
        "directive-selector": [
            true,
            "attribute",
            "directivePrefix",
            "camelCase"
        ],
        "component-selector": [
            true,
            "element",
            "compoenent-prefix",
            "kebab-case"
        ]
    }
}

Changing in that file will fix the problem.

Actually, with Angular Cli, you can just change the "prefix" tag, inside the "apps" array on your angular-cli.json, located on the root app.

Changing for "TheBestPrefix", like this.

"apps": [
  {
    "root": "src",
    "outDir": "dist",
    "assets": [
      "assets",
      "favicon.ico"
    ],
    "index": "index.html",
    "main": "main.ts",
    "test": "test.ts",
    "tsconfig": "tsconfig.json",
    "prefix": "TheBestPrefix",
    "mobile": false,
    "styles": [
      "styles.css"
    ],
    "scripts": [],
    "environments": {
      "source": "environments/environment.ts",
      "dev": "environments/environment.ts",
      "prod": "environments/environment.prod.ts"
    }
  }
]

When you generate a new component using CLI, ng g component mycomponent the component tag will have the following name "TheBestPrefix-mycomponent"

1. Adjust your angular-cli.json: "prefix": "defaultPrefix" so that angular-cli will use that for generating components.

2. Ajust tslint.json like this:

   "directive-selector": [
     true,
     "attribute",
     ["prefix1", "prefix2", "prefix3"],
     "camelCase"
   ],
   "component-selector": [
     true,
     "element",
     ["prefix1", "prefix2", "prefix3"],
     "kebab-case"
   ],