33 lines
953 B
JavaScript
33 lines
953 B
JavaScript
/* -*- mode: js2; js2-basic-offset: 4; indent-tabs-mode: nil -*- */
|
|
|
|
// parse:
|
|
// @params: caller-provided parameter object, or %null
|
|
// @default: function-provided defaults object
|
|
// @allowExtras: whether or not to allow properties not in @default
|
|
//
|
|
// Examines @params and fills in default values from @defaults for
|
|
// any properties in @defaults that don't appear in @params. If
|
|
// @allowExtras is not %true, it will throw an error if @params
|
|
// contains any properties that aren't in @defaults.
|
|
//
|
|
// If @params is %null, this returns @defaults.
|
|
//
|
|
// Return value: the updated params
|
|
function parse(params, defaults, allowExtras) {
|
|
if (!params)
|
|
return defaults;
|
|
|
|
if (!allowExtras) {
|
|
for (let prop in params) {
|
|
if (!(prop in defaults))
|
|
throw new Error('Unrecognized parameter "' + prop + '"');
|
|
}
|
|
}
|
|
|
|
for (let prop in defaults) {
|
|
if (!(prop in params))
|
|
params[prop] = defaults[prop];
|
|
}
|
|
|
|
return params;
|
|
} |