NodeJs : npm run-script "sciptname" in package.json

npm run-script scriptName

This actually looks for "scriptName" in package.json  in "scripts" part of package.json

npm run-script build_dev

"name": "metronic-angular",

    "version": "6.1.8",

    "description": "Packages used by Angular",

    "scripts": {

        "ng": "ng",

        "start": "node --max_old_space_size=8192 node_modules/@angular/cli/bin/ng serve",

        "build": "ng build",

        "build_dev": "node --max_old_space_size=8192 node_modules/@angular/cli/bin/ng build --sourceMap=false --base-href=\"/\" --aot --output-hashing none",

        "build_qa": "node --max_old_space_size=8192 node_modules/@angular/cli/bin/ng build --configuration=qa --base-href=\"/\" --output-hashing none",

        "build_dev2": "node --max_old_space_size=8192 node_modules/@angular/cli/bin/ng build --configuration=dev2 --base-href=\"/\" --output-hashing none",

        "build_qa2": "node --max_old_space_size=8192 node_modules/@angular/cli/bin/ng build --configuration=qa2 --base-href=\"/\" --output-hashing none",

        "build_stage": "node --max_old_space_size=8192 node_modules/@angular/cli/bin/ng build --configuration=staging --base-href=\"/\" --output-hashing none",

        "build_prod": "node --max_old_space_size=8192 node_modules/@angular/cli/bin/ng build --prod --base-href=\"/\" --output-hashing none",

        "test": "ng test",

        "lint": "ng lint",

        "e2e": "ng e2e",

        "bundle-report": "webpack-bundle-analyzer dist/stats.json",

        "rtl": "webpack"

    },