vscode task get value from json code example

Example: vs code variable reference

${workspaceFolder} - the path of the folder opened in VS Code
${workspaceFolderBasename} - the name of the folder opened in VS Code without any slashes (/)
${file} - the current opened file
${relativeFile} - the current opened file relative to workspaceFolder
${relativeFileDirname} - the current opened file's dirname relative to workspaceFolder
${fileBasename} - the current opened file's basename
${fileBasenameNoExtension} - the current opened file's basename with no file extension
${fileDirname} - the current opened file's dirname
${fileExtname} - the current opened file's extension
${cwd} - the task runner's current working directory on startup
${lineNumber} - the current selected line number in the active file
${selectedText} - the current selected text in the active file
${execPath} - the path to the running VS Code executable
${defaultBuildTask} - the name of the default build task