Is there a JavaScript module that makes it easy to map arguments to parameters? Here is how I envision it working:<\/p>\n
\nvar arguments = assignArguments(arguments, ‘p1’, ‘p2’, [{‘p3’: 0}, ‘p4’], {‘p5’: ‘unknown’});<\/p>\n<\/blockquote>\n
Within a function, you would call this to generate an object that associated a parameter with an argument. Parameters defined within an array or inline object would be considered optional, where inline objects would permit assigning default values. All other parameters are considered “required”.<\/p>\n
Here are some sample inputs\/outpus:<\/p>\n
foo(1): { p1: 1, p3: 0, p5: 'unknown' } \/\/ no p2 (aka undefined) \nfoo(1, 2): { p1: 1, p2: 2, p3: 0, p5: 'unknown' } \nfoo(1, 2, 3): { p1: 1, p2: 2, p3: 0, p4: 3, p5: 'unknown' } \nfoo(1, 2, 3, 4): { p1: 1, p2: 2, p3: 3, p4: 4, p5: 'unknown' } \nfoo(1, 2, 3, 4, 5): { p1: 1, p2: 2, p3: 3, p4: 4, p5: 5 }\n<\/code><\/pre>\nI am hoping a library like this already exists. This logic gets repeated a lot and I want to eliminate it if possible.<\/p>\n
Is anyone aware of a library like this? If not, can someone send me down the right path for implementing one?<\/p>\n
\n
- \n
I went ahead and thought of a way of doing this myself. It involves parsing an object graph made up of strings, arrays and objects. It’s quite long, but it works well.<\/p>\n
function assignArguments(values, expression) { \n \/\/ determine how many arguments are needed for each parameter\n \/\/ grab all of the defaults, too\n var needed = 1;\n var argsNeeded = {};\n var defaults = {};\n var queue = [expression]; \n for (var queueIndex = 0; queueIndex < queue.length; ++queueIndex) {\n var node = queue[queueIndex];\n if (typeof node === 'string') {\n \/\/ the node is a required parameter\n argsNeeded[node] = needed;\n ++needed;\n } else if (node instanceof Array) {\n \/\/ the node is a list of parameters\n for (var index = 0; index !== node.length; ++index) {\n queue.push(node[index]);\n }\n } else {\n \/\/ the node is a list of optional parameters with defaults\n \/\/ make sure there isn't more than one parameter\n var count = 0;\n for (var key in node) {\n if (node.hasOwnProperty(key)) {\n if (count !== 0) {\n throw new Error('A default parameter list had more than one value.');\n }\n defaults[key] = node[key];\n queue.push(key);\n ++count;\n }\n }\n }\n }\n\n \/\/ determine the order that the parameters appear\n var parameters = [];\n var stack = [expression];\n while (stack.length > 0) {\n var node = stack.pop();\n if (typeof node === 'string') {\n \/\/ the node is a required parameter\n parameters.push(node);\n } else if (node instanceof Array) {\n \/\/ the node is a list of parameters\n var index = node.length;\n while (index !== 0) {\n --index;\n stack.push(node[index]);\n }\n } else {\n \/\/ the node is an optional parameter with defaults\n \/\/ we'll check for multiple parameters\n var count = 0;\n for (var key in node) {\n if (node.hasOwnProperty(key)) {\n if (count > 0) {\n throw new Error('A default parameter list had more than one value.');\n }\n stack.push(key);\n ++count;\n }\n }\n }\n }\n\n var result = {};\n var valueIndex = 0;\n for (var index = 0; index !== parameters.length; ++index) {\n var parameter = parameters[index];\n var needed = argsNeeded[parameter];\n if (needed > values.length) {\n if (parameter in defaults) {\n result[parameter] = defaults[parameter];\n }\n } else {\n result[parameter] = values[valueIndex];\n ++valueIndex;\n }\n }\n\n return result;\n}\n<\/code><\/pre>\nAnd here is an example using it.<\/p>\n
function foo() {\n var params = assignArguments(arguments, ['p1', 'p2', [{p3:0}, 'p4'], {p5: 'unknown'}]);\n return params;\n}\n\nconsole.log(foo(1));\nconsole.log(foo(1, 2));\nconsole.log(foo(1, 2, 3));\nconsole.log(foo(1, 2, 3, 4));\nconsole.log(foo(1, 2, 3, 4, 5));\n<\/code><\/pre>\n<\/li>\n<\/ol>\nOriginally posted 2013-11-09 21:05:29. <\/small><\/p>","protected":false},"excerpt":{"rendered":"
Is there a JavaScript module that makes it easy to map arguments to parameters? Here is how I envision it working: var arguments = assignArguments(arguments, ‘p1’, ‘p2’, [{‘p3’: 0}, ‘p4’], {‘p5’: ‘unknown’}); Within a function, you would call this to generate an object that associated a parameter with an argument. Parameters defined within an array […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-580","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts\/580","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/comments?post=580"}],"version-history":[{"count":0,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts\/580\/revisions"}],"wp:attachment":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/media?parent=580"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/categories?post=580"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/tags?post=580"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}