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Add _.before.

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This commit is contained in:
John-David Dalton
2014-07-01 09:27:43 -07:00
parent 6622922468
commit b084210705
2 changed files with 103 additions and 36 deletions
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76
lodash.js
View File

@@ -732,14 +732,14 @@
* implicitly or explicitly included in the build.
*
* The chainable wrapper functions are:
* `after`, `assign`, `at`, `bind`, `bindAll`, `bindKey`, `callback`, `chain`,
* `chunk`, `compact`, `compose`, `concat`, `constant`, `countBy`, `create`,
* `curry`, `debounce`, `defaults`, `defer`, `delay`, `difference`, `drop`,
* `dropRight`, `dropRightWhile`, `dropWhile`, `filter`, `flatten`, `forEach`,
* `forEachRight`, `forIn`, `forInRight`, `forOwn`, `forOwnRight`, `functions`,
* `groupBy`, `indexBy`, `initial`, `intersection`, `invert`, `invoke`, `keys`,
* `keysIn`, `map`, `mapValues`, `matches`, `memoize`, `merge`, `mixin`,
* `negate`, `noop`, `omit`, `once`, `pairs`, `partial`, `partialRight`,
* `after`, `assign`, `at`, `before`, `bind`, `bindAll`, `bindKey`, `callback`,
* `chain`, `chunk`, `compact`, `compose`, `concat`, `constant`, `countBy`,
* `create`, `curry`, `debounce`, `defaults`, `defer`, `delay`, `difference`,
* `drop`, `dropRight`, `dropRightWhile`, `dropWhile`, `filter`, `flatten`,
* `forEach`, `forEachRight`, `forIn`, `forInRight`, `forOwn`, `forOwnRight`,
* `functions`, `groupBy`, `indexBy`, `initial`, `intersection`, `invert`,
* `invoke`, `keys`, `keysIn`, `map`, `mapValues`, `matches`, `memoize`, `merge`,
* `mixin`, `negate`, `noop`, `omit`, `once`, `pairs`, `partial`, `partialRight`,
* `partition`, `pick`, `pluck`, `property`, `pull`, `pullAt`, `push`, `range`,
* `reject`, `remove`, `rest`, `reverse`, `shuffle`, `slice`, `sort`, `sortBy`,
* `splice`, `take`, `takeRight`, `takeRightWhile`, `takeWhile`, `tap`,
@@ -5440,14 +5440,13 @@
/*--------------------------------------------------------------------------*/
/**
* Creates a function that executes `func`, with the `this` binding and
* arguments of the created function, only after being called `n` times.
* The opposite of `_.before`; this method creates a function that executes
* `func` only after it is called `n` times.
*
* @static
* @memberOf _
* @category Function
* @param {number} n The number of times the function must be called before
* `func` is executed.
* @param {number} n The number of calls before `func` is executed.
* @param {Function} func The function to restrict.
* @returns {Function} Returns the new restricted function.
* @example
@@ -5475,6 +5474,37 @@
};
}
/**
* Creates a function that executes `func`, with the `this` binding and
* arguments of the created function, until it is called `n` times.
*
* @static
* @memberOf _
* @category Function
* @param {number} n The number of times `func` may be executed.
* @param {Function} func The function to restrict.
* @returns {Function} Returns the new restricted function.
* @example
*
* jQuery('#add').on('click', _.before(5, addContactToList));
* // => allows adding up to 5 contacts to the list
*/
function before(n, func) {
var result;
if (!isFunction(func)) {
throw new TypeError(funcErrorText);
}
n = nativeIsFinite(n = +n) ? n : 0;
return function() {
if (--n > 0) {
result = func.apply(this, arguments);
} else {
func = null;
}
return result;
};
}
/**
* Creates a function that invokes `func` with the `this` binding of `thisArg`
* and prepends any additional `bind` arguments to those provided to the bound
@@ -6028,6 +6058,7 @@
*
* @static
* @memberOf _
* @type Function
* @category Function
* @param {Function} func The function to restrict.
* @returns {Function} Returns the new restricted function.
@@ -6038,25 +6069,7 @@
* initialize();
* // `initialize` executes `createApplication` once
*/
function once(func) {
var ran,
result;
if (!isFunction(func)) {
throw new TypeError(funcErrorText);
}
return function() {
if (ran) {
return result;
}
ran = true;
result = func.apply(this, arguments);
// clear the `func` variable so the function may be garbage collected
func = null;
return result;
};
}
var once = partial(before, 2);
/**
* Creates a function that invokes `func` with any additional `partial` arguments
@@ -8888,6 +8901,7 @@
lodash.after = after;
lodash.assign = assign;
lodash.at = at;
lodash.before = before;
lodash.bind = bind;
lodash.bindAll = bindAll;
lodash.bindKey = bindKey;

63
test/test.js
View File

@@ -621,15 +621,29 @@
}
test('should create a function that executes `func` after `n` calls', 4, function() {
strictEqual(after(5, 5), 1, 'after(n) should execute `func` after being called `n` times');
strictEqual(after(5, 4), 0, 'after(n) should not execute `func` unless called `n` times');
strictEqual(after(5, 4), 0, 'after(n) should not execute `func` before being called `n` times');
strictEqual(after(0, 0), 0, 'after(0) should not execute `func` immediately');
strictEqual(after(0, 1), 1, 'after(0) should execute `func` when called once');
});
test('should coerce non-finite `n` values to `0`', 3, function() {
_.each([-Infinity, NaN, Infinity], function(n) {
strictEqual(after(n, 1), 1);
test('should coerce non-finite `n` values to `0`', 1, function() {
var values = [-Infinity, NaN, Infinity],
expected = _.map(values, _.constant(1));
var actual = _.map(values, function(n) {
return after(n, 1);
});
deepEqual(actual, expected);
});
test('should not set a `this` binding', 2, function() {
var after = _.after(1, function() { return ++this.count; }),
object = { 'count': 0, 'after': after };
object.after();
strictEqual(object.after(), 2);
strictEqual(object.count, 2);
});
}());
@@ -724,6 +738,44 @@
/*--------------------------------------------------------------------------*/
QUnit.module('lodash.before');
(function() {
function before(n, times) {
var count = 0;
_.times(times, _.before(n, function() { count++; }));
return count;
}
test('should create a function that executes `func` after `n` calls', 4, function() {
strictEqual(before(5, 4), 4, 'before(n) should execute `func` before being called `n` times');
strictEqual(before(5, 6), 4, 'before(n) should not execute `func` after being called `n - 1` times');
strictEqual(before(0, 0), 0, 'before(0) should not execute `func` immediately');
strictEqual(before(0, 1), 0, 'before(0) should not execute `func` when called');
});
test('should coerce non-finite `n` values to `0`', 1, function() {
var values = [-Infinity, NaN, Infinity],
expected = _.map(values, _.constant(0));
var actual = _.map(values, function(n) {
return before(n);
});
deepEqual(actual, expected);
});
test('should not set a `this` binding', 2, function() {
var before = _.before(2, function() { return ++this.count; }),
object = { 'count': 0, 'before': before };
object.before();
strictEqual(object.before(), 1);
strictEqual(object.count, 1);
});
}());
/*--------------------------------------------------------------------------*/
QUnit.module('lodash.bind');
(function() {
@@ -11316,6 +11368,7 @@
var rejectFalsey = [
'after',
'before',
'bind',
'compose',
'curry',
@@ -11401,7 +11454,7 @@
});
});
test('should throw a TypeError for falsey arguments', 16, function() {
test('should throw a TypeError for falsey arguments', 17, function() {
_.each(rejectFalsey, function(methodName) {
var expected = _.map(falsey, _.constant(true)),
func = _[methodName];