js-eval - Execute JavaScript, parse JSON, on vanilla macOS (no dev tools or packages installed)

js-eval.sh

#!/bin/sh

alias js-eval="osascript -l JavaScript -e"

# examples:

js-eval "1+1"
# 2

js-eval "Math.PI"
# 3.141592653589793

JSON_STRING="[\"zero\", \"one\", \"two\"]"
js-eval "JSON.parse('$JSON_STRING')[1]"
# one

# advanced example:
# read from stdin and then parse as JSON
js-eval "stdin = $.NSString.alloc.initWithDataEncoding($.NSFileHandle.fileHandleWithStandardInput.readDataToEndOfFile, $.NSUTF8StringEncoding).js;
         JSON.parse(stdin)"