-
Notifications
You must be signed in to change notification settings - Fork 2
Transitioning from Underscore.js
We do not use underscore.js. Instead, we use built in JavaScript functions and write a small handful of our own. In this page, we describe our alternatives to using underscore.js
A major design goal in underscore.js was that it not extend any existing JavaScript objects. This makes sense for underscore.js, because it is used by many developers in many different contexts, and some of those developers might not be OK with extending the existing JavaScript classes. However, it has some nasty consequences.
For instance, underscore.js has a function _.bind, which is basically identical to the built in function Function.prototype.bind. underscore.js has to write a version of the .bind function because old browsers don't have native support. And if can't simply detect if native support already exists and gracefully upgrade to the native implementation if possible, because that would be extending existing JavaScript objects. The result is that with underscore.js you have to write _.bind(f, obj) instead of the more modern (and more efficient) f.bind(obj).
Since we are only writing code for ourselves, we do not need to worry about the dangers of extending existing objects.
Note: Not every underscore.js function has a direct alternative in our style. In these cases, the alternatives is generally just a combination of two functions. If you feel that some function from underscore.js was extremely useful, and we are not currently providing a direct alternative, feel free to make the alternative yourself (preferably by extending existing JavaScript object). In the mean time, we provide code for how the the alternatives can be created.
Use Array.prototype.each, which is equivalent to the native function Array.prototype.forEach, or $.each.
So _.each(array, fun) becomes array.each(fun)
Use the native function Array.prototype.map.
So _.map(array, fun) becomes array.map(fun)
Use the native function Array.prototype.reduce.
So _.reduce(array, fun, init) becomes array.reduce(fun, init)
Use the native function Array.prototype.reduceRight.
So _.reduceRight(array, fun, init) becomes array.reduceRight(fun, init)
No direct alternative. Use array.filter(fun)[0] instead of _.find(array, fun)
Use the native function Array.prototype.filter.
So _.filter(array, fun) becomes array.filter(fun)
No direct alternative. Use Array.prototype.filter and just create an anonymous function to check the desired properties.
See the alternative to _.where and _.find
No direct alternative. Use array.filter(op.not.o(fun)) instead of _.reject(array, fun)
Use the native function Array.prototype.every.
So _.every(array, fun) becomes array.every(fun)
Use the native function Array.prototype.some.
So _.some(array, fun) becomes array.some(fun)
No direct alternative. Use Array.prototype.map
So _.invoke(list, funName) becomes list.map(eval(funName))
No direct alternative. Use array.map(op.get.C($, 'prop')) instead of _.pluck(array, 'prop')
Use Array.prototype.max.
So _.max(array) becomes array.max()
Use Array.prototype.min.
So _.min(array) becomes array.min()
Use the native function Array.prototype.sort, though it is not quite the same thing.
No direct alternative.
No direct alternative.
No direct alternative.
No direct alternative.
No direct alternative.
Use $.makeArray
So _.toArray(obj) becomes $.makeArray(obj)
No direct alternative, but Object.keys(obj).length is roughly equivalent
Please use array[0] instead of _.first(array)
Please use Array.prototype.slice.
So _.initial(array, n) becomes array.slice(0, n)
Please use array[array.length-1] instead of _.last(array)
Please use Array.prototype.slice.
So _.rest(array) becomes array.slice(1)
Please use Array.prototype.filter.
So _.compact(array) becomes array.filter(op.id)
No direct alternative
No direct alternative. Please use Array.prototype.filter.
No direct alternative. Use $.merge, though it is not quite the same thing.
No direct alternative
No direct alternative
No direct alternative
No direct alternative
No direct alternative
Please use Array.prototype.indexOf or $.inArray
So _.indexOf(array, x) becomes array.indexOf(x)
Please use Array.prototype.lastIndexOf.
So _.lastIndexOf(array, x) becomes array.lastIndexOf(x)
No direct alternative
Not really the same thing, but you could use Array.tabulate
Use the native function Function.prototype.bind.
So _.bind(fun, x) becomes fun.bind(x)
No direct alternative
Use Function.prototype.c
So _.partial(fun, x) becomes fun.c(x)
No direct alternative
Use the native function setTimeout
So _.delay(fun, wait) becomes setTimeout(fun, wait)
Use the native function setTimeout with a wait of 0
So _.defer(fun) becomes setTimeout(fun, 0)
No direct alternative
No direct alternative
No direct alternative
No direct alternative
No direct alternative. Use f.c(g) instead of _.wrap(f, g)
Use Function.prototype.o
So _.compose(f, g) becomes f.o(g)
Use the native function Object.keys
So _.keys(obj) becomes Object.keys(obj)
No direct alternative. Use Object.keys(obj).map(op.get.c(obj) instead of _.values(obj)
No direct alternative.
No direct alternative.
No direct alternative. Use Object.keys(obj).filter(function(k) {return obj[k] instanceof Function;}) instead of _.functions(obj)
Use $.extend
So obj1 = _.extend(obj1, obj2) becomes $.extend(obj1, obj2)
No direct alternative.
No direct alternative.
Use $.extend, but reverse the order
No direct alternative. Use $.extend(Array.isArray(obj) ? [] : {}, obj) instead of _.clone(obj)
Not applicable.
Use the native function Object.prototype.hasOwnProperty
So _.has(obj, prop) becomes obj.hasOwnProperty(prop)
No direct alternative.
Use $.isEmptyObject
So _.isEmpty(obj) becomes $.isEmptyObject(obj)
No direct alternative.
Use the native method Array.isArray
So _.isArray(array) becomes Array.isArray(array)
Use the typeof operator.
So _.isObject(x) becomes typeof x == "object"
No direct alternative. Use x.toString() == [object Arguments] instead of _.isArguments(x)
Use $.isFunction
So _.isFunction(obj) becomes $.isFunction(obj)
Use $.type
So _.isString(x) becomes $.type(x) == "string"
Use $.isNumeric
So _.isNumber(x) becomes $.isNumeric(x)
No direct alternative.
Use the typeof operator.
So _.isBoolean(x) becomes typeof x == "boolean"
Use $.type
So _.isDate(x) becomes $.type(x) == "date"
Use $.type
So _.isRegExp(x) becomes $.type(x) == "regexp"
Use the native function isNaN, though it is not quite the same thing. In the future, you might be able to use Number.isNaN, which is more similar.
So _.isNaN(x) becomes isNaN(x)
Use the native operator ===.
So _.isNull(x) becomes x === null
Use the native operator ===.
So _.isUndefined(x) becomes x === undedined
Not applicable.
Use op.id
So _.identity(x) becomes op.id(x)
No direct alternative.
Use Math.random
So _.random(min, max) becomes Math.random()*(max-min+1)|0 + min
Not applicable.
No direct alternative.
Use the native function encodeURI
So _.escape(str) becomes encodeURI(str)
Use the native function decodeURI
So _.unescape(str) becomes decodeURI(str)
No direct alternative.
We have our own internal templating engine.