I have some code that takes a SP List item column (a news article tagged to one or more choice categories) and want to show that to users who have a user profile property with one or more categories they subscribe to (csv). When I display my news, I only want to show items that match what the user subscribes to.

I can run this TS online in an editor and it works (see snippet https://www.typescriptlang.org/play/index.html#src=Array.prototype.diff%20%3D%20function%20(arr2)%20%7B%0D%0Avar%20ret%20%3D%20%5B%5D%3B%0D%0A%20%20for%20(var%20i%20in%20this)%20%7B%0D%0A%20%20%20%20%20if%20(arr2.indexOf(this%5Bi%5D)%20%3E%20-1)%20%7B%0D%0A%20%20%20%20%20%20%20%20ret.push(this%5Bi%5D)%3B%0D%0A%20%20%20%20%20%20%7D%0D%0A%20%20%7D%0D%0A%20%20return%20ret%3B%0D%0A%7D%3B%0D%0Avar%20array1%20%3D%20%5B%22Panda%22%2C%20%22Zebra%22%2C%20%22Lion%22%2C%20%22Cat%22%2C%20%22Dog%22%2C%20%22Fish%22%2C%20%22whatever%22%2C%20%22Bird%22%5D%3B%0D%0Avar%20array2%20%3D%20%5B%22Panda%22%2C%20%22Cat%22%5D%3B%0D%0A%0D%0Aconsole.log(array1.diff(array2))%3B ) but cannot validate or build this code in my new SPFX web part using the latest Yeoman templates. It says (TS) property “diff” does not exist on type ‘any[]’

Array.prototype.diff = function (arr2) { var ret = [];   for (var i in this) {      if (arr2.indexOf(this[i]) > -1) {         ret.push(this[i]);       }   }   return ret; }; var array1 = ["Panda", "Zebra", "Lion", "Cat", "Dog", "Fish", "whatever", "Bird"]; var array2 = ["Panda", "Cat"];  console.log(array1.diff(array2)); 

OOTB from Yeoman theres types es6-promise with es5 lib and targets.

How do I get diff to work? How can I see if es5 or es6 is “loaded” on my ts code page?

gulp package error:

PS C:\VS\ClientProject> gulp bundle --ship Build target: SHIP [13:41:22] Using gulpfile C:\VS\ClientProject\gulpfile.js [13:41:22] Starting gulp [13:41:22] Starting 'bundle'... [13:41:22] Starting subtask 'configure-sp-build-rig'... [13:41:22] Finished subtask 'configure-sp-build-rig' after 12 ms [13:41:22] Starting subtask 'pre-copy'... [13:41:22] Finished subtask 'pre-copy' after 14 ms [13:41:22] Starting subtask 'copy-static-assets'... [13:41:22] Starting subtask 'sass'... [13:41:24] Finished subtask 'sass' after 1.54 s [13:41:24] Starting subtask 'tslint'... [13:41:25] Starting subtask 'typescript'... [13:41:25] [typescript] TypeScript version: 2.4.2 [13:41:26] Finished subtask 'copy-static-assets' after 3.21 s Warning: no-duplicate-case rule is deprecated. Replace your usage with the TSLint no-duplicate-switch-case rule. Warning: valid-typeof rule is deprecated. Replace your usage with the TSLint typeof-compare rule. [13:41:26] Warning - tslint - src\webparts\clientProject\clientProjectWebPart.ts(102,45): error no-function-expression: Use arrow function instead of function expression [13:41:26] Warning - tslint - src\webparts\clientProject\clientProjectWebPart.ts(105,30): error no-function-expression: Use arrow function instead of function expression [13:41:26] Warning - tslint - src\webparts\clientProject\clientProjectWebPart.ts(115,14): error no-function-expression: Use arrow function instead of function expression [13:41:26] Warning - tslint - src\webparts\clientProject\clientProjectWebPart.ts(97,142): error no-shadowed-variable: Shadowed name: 'jQuery' [13:41:26] Finished subtask 'tslint' after 2.44 s [13:41:28] Error - typescript - src\webparts\clientProject\clientProjectWebPart.ts(137,20): error TS2339: Property 'diff' does not exist on type 'any[]'. [13:41:28] Error - typescript - src\webparts\clientProject\clientProjectWebPart.ts(149,23): error TS2339: Property 'diff' does not exist on type 'string[]'. [13:41:28] Error - 'typescript' sub task errored after 2.8 s  TypeScript error(s) occurred. [13:41:28] 'bundle' errored after 6.03 s [13:41:28] [13:41:29] ==================[ Finished ]================== Warning - tslint - src/webparts/clientProject/clientProjectWebPart.ts(102,45): error no-function-expression: Use arrow function instead of function expression Warning - tslint - src/webparts/clientProject/clientProjectWebPart.ts(105,30): error no-function-expression: Use arrow function instead of function expression Warning - tslint - src/webparts/clientProject/clientProjectWebPart.ts(115,14): error no-function-expression: Use arrow function instead of function expression Warning - tslint - src/webparts/clientProject/clientProjectWebPart.ts(97,142): error no-shadowed-variable: Shadowed name: 'jQuery' Error - typescript - src/webparts/clientProject/clientProjectWebPart.ts(137,20): error TS2339: Property 'diff' does not exist on type 'any[]'. Error - typescript - src/webparts/clientProject/clientProjectWebPart.ts(149,23): error TS2339: Property 'diff' does not exist on type 'string[]'. Error - 'typescript' sub task errored after 2.8 s  TypeScript error(s) occurred. [13:41:29] Project r-net-homepage-news version: 0.0.1 [13:41:29] Build tools version: 3.2.7 [13:41:29] Node version: v6.10.3 [13:41:29] Total duration: 11 s [13:41:29] Task warnings: 4 [13:41:29] Task errors: 3 

tsconfig.json

{   "compilerOptions": {     "target": "es5",     "forceConsistentCasingInFileNames": true,     "module": "commonjs",     "jsx": "react",     "declaration": true,     "sourceMap": true,     "experimentalDecorators": true,     "skipLibCheck": true,     "typeRoots": [       "./node_modules/@types",       "./node_modules/@microsoft"     ],     "types": [       "es6-promise",       "webpack-env"     ],     "lib": [       "es5",       "dom",       "es2015.collection"     ]   } } 

Thanks,

Eric Schrader