思维导图备注

Lodash v4.7.11 Document
首页 白天 夜间 BookChat 小程序 小程序 阅读
  • 书签 我的书签
  • 添加书签 添加书签 移除书签 移除书签

_.isUndefined(value)

 来源:lodash.com 浏览 421 扫码 分享 2019-05-15 08:07:18
  • _.isUndefined(value)
    • Since
    • Arguments
    • Returns
    • Example

    _.isUndefined(value)

    sourcenpm package

    Checks if value is undefined.

    Since

    0.1.0

    Arguments

    • value (*): The value to check.

    Returns

    (boolean): Returns true if value is undefined, else false.

    Example

    1. _.isUndefined(void 0);
      // => true
       
      _.isUndefined(null);
      // => false
    当前内容版权归 lodash.com 或其关联方所有，如需对内容或内容相关联开源项目进行关注与资助，请访问 lodash.com .
    上一篇:
    下一篇:
    • 书签
    • 添加书签 移除书签
    • Introduction
    • “Array” Methods
      • _.chunk(array, [size=1])
      • _.compact(array)
      • _.concat(array, [values])
      • _.difference(array, [values])
      • _.differenceBy(array, [values], [iteratee=_.identi
      • _.differenceWith(array, [values], [comparator])
      • _.drop(array, [n=1])
      • _.dropRight(array, [n=1])
      • _.dropRightWhile(array, [predicate=_.identity])
      • _.dropWhile(array, [predicate=_.identity])
      • _.fill(array, value, [start=0], [end=array.length])
      • _.findIndex(array, [predicate=_.identity], [fromIn
      • _.findLastIndex(array, [predicate=_.identity], [fr
      • _.flatten(array)
      • _.flattenDeep(array)
      • _.flattenDepth(array, [depth=1])
      • _.fromPairs(pairs)
      • _.head(array)
      • _.indexOf(array, value, [fromIndex=0])
      • _.initial(array)
      • _.intersection([arrays])
      • _.intersectionBy([arrays], [iteratee=_.identity])
      • _.intersectionWith([arrays], [comparator])
      • _.join(array, [separator=','])
      • _.last(array)
      • _.lastIndexOf(array, value, [fromIndex=array.length-1])
      • _.nth(array, [n=0])
      • _.pull(array, [values])
      • _.pullAll(array, values)
      • _.pullAllBy(array, values, [iteratee=_.identity])
      • _.pullAllWith(array, values, [comparator])
      • _.pullAt(array, [indexes])
      • _.remove(array, [predicate=_.identity])
      • _.reverse(array)
      • _.slice(array, [start=0], [end=array.length])
      • _.sortedIndex(array, value)
      • _.sortedIndexBy(array, value, [iteratee=_.identity
      • _.sortedIndexOf(array, value)
      • _.sortedLastIndex(array, value)
      • _.sortedLastIndexBy(array, value, [iteratee=_.iden
      • _.sortedLastIndexOf(array, value)
      • _.sortedUniq(array)
      • _.sortedUniqBy(array, [iteratee])
      • _.tail(array)
      • _.take(array, [n=1])
      • _.takeRight(array, [n=1])
      • _.takeRightWhile(array, [predicate=_.identity])
      • _.takeWhile(array, [predicate=_.identity])
      • _.union([arrays])
      • _.unionBy([arrays], [iteratee=_.identity])
      • _.unionWith([arrays], [comparator])
      • _.uniq(array)
      • _.uniqBy(array, [iteratee=_.identity])
      • _.uniqWith(array, [comparator])
      • _.unzip(array)
      • _.unzipWith(array, [iteratee=_.identity])
      • _.without(array, [values])
      • _.xor([arrays])
      • _.xorBy([arrays], [iteratee=_.identity])
      • _.xorWith([arrays], [comparator])
      • _.zip([arrays])
      • _.zipObject([props=[]], [values=[]])
      • _.zipObjectDeep([props=[]], [values=[]])
      • .zipWith([arrays], [iteratee=.identity])
    • “Collection” Methods
      • _.countBy(collection, [iteratee=_.identity])
      • _.every(collection, [predicate=_.identity])
      • _.filter(collection, [predicate=_.identity])
      • _.find
      • _.findLast
      • _.flatMap(collection, [iteratee=_.identity])
      • _.flatMapDeep(collection, [iteratee=_.identity])
      • _.flatMapDepth
      • _.forEach(collection, [iteratee=_.identity])
      • _.forEachRight(collection, [iteratee=_.identity])
      • _.groupBy(collection, [iteratee=_.identity])
      • _.includes(collection, value, [fromIndex=0])
      • _.invokeMap(collection, path, [args])
      • _.keyBy(collection, [iteratee=_.identity])
      • _.map(collection, [iteratee=_.identity])
      • _.orderBy
      • _.partition(collection, [predicate=_.identity])
      • _.reduce
      • _.reduceRight
      • _.reject(collection, [predicate=_.identity])
      • _.sample(collection)
      • _.sampleSize(collection, [n=1])
      • _.shuffle(collection)
      • _.size(collection)
      • _.some(collection, [predicate=_.identity])
      • _.sortBy(collection, [iteratees=[_.identity]])
    • “Date” Methods
    • “Function” Methods
      • _.after(n, func)
      • _.ary(func, [n=func.length])
      • _.before(n, func)
      • _.bind(func, thisArg, [partials])
      • _.bindKey(object, key, [partials])
      • _.curry(func, [arity=func.length])
      • _.curryRight(func, [arity=func.length])
      • _.debounce(func, [wait=0], [options={}])
      • _.defer(func, [args])
      • _.delay(func, wait, [args])
      • _.flip(func)
      • _.memoize(func, [resolver])
      • _.negate(predicate)
      • _.once(func)
      • _.overArgs(func, [transforms=[_.identity]])
      • _.partial(func, [partials])
      • _.partialRight(func, [partials])
      • _.rearg(func, indexes)
      • _.rest(func, [start=func.length-1])
      • _.spread(func, [start=0])
      • _.throttle(func, [wait=0], [options={}])
      • _.unary(func)
      • _.wrap(value, [wrapper=identity])
    • “Lang” Methods
      • _.castArray(value)
      • _.clone(value)
      • _.cloneDeep(value)
      • _.cloneDeepWith(value, [customizer])
      • _.cloneWith(value, [customizer])
      • _.conformsTo(object, source)
      • _.eq(value, other)
      • _.gt(value, other)
      • _.gte(value, other)
      • _.isArguments(value)
      • _.isArray(value)
      • _.isArrayBuffer(value)
      • _.isArrayLike(value)
      • _.isArrayLikeObject(value)
      • _.isBoolean(value)
      • _.isBuffer(value)
      • _.isDate(value)
      • _.isElement(value)
      • _.isEmpty(value)
      • _.isEqual(value, other)
      • _.isEqualWith(value, other, [customizer])
      • _.isError(value)
      • _.isFinite(value)
      • _.isFunction(value)
      • _.isInteger(value)
      • _.isLength(value)
      • _.isMap(value)
      • _.isMatch(object, source)
      • _.isMatchWith(object, source, [customizer])
      • _.isNaN(value)
      • _.isNative(value)
      • _.isNil(value)
      • _.isNull(value)
      • _.isNumber(value)
      • _.isObject(value)
      • _.isObjectLike(value)
      • _.isPlainObject(value)
      • _.isRegExp(value)
      • _.isSafeInteger(value)
      • _.isSet(value)
      • _.isString(value)
      • _.isSymbol(value)
      • _.isTypedArray(value)
      • _.isUndefined(value)
      • _.isWeakMap(value)
      • _.isWeakSet(value)
      • _.lt(value, other)
      • _.lte(value, other)
      • _.toArray(value)
      • _.toFinite(value)
      • _.toInteger(value)
      • _.toLength(value)
      • _.toNumber(value)
      • _.toPlainObject(value)
      • _.toSafeInteger(value)
      • _.toString(value)
    • “Math” Methods
      • _.add(augend, addend)
      • _.ceil(number, [precision=0])
      • _.divide(dividend, divisor)
      • _.floor(number, [precision=0])
      • _.max(array)
      • _.maxBy(array, [iteratee=_.identity])
      • _.mean(array)
      • _.meanBy(array, [iteratee=_.identity])
      • _.min(array)
      • _.minBy(array, [iteratee=_.identity])
      • _.multiply(multiplier, multiplicand)
      • _.round(number, [precision=0])
      • _.subtract(minuend, subtrahend)
      • _.sum(array)
      • _.sumBy(array, [iteratee=_.identity])
    • “Number” Methods
    • “Object” Methods
      • _.assign(object, [sources])
      • _.assignIn(object, [sources])
      • _.assignInWith(object, sources, [customizer])
      • _.assignWith(object, sources, [customizer])
      • _.at(object, [paths])
      • _.create(prototype, [properties])
      • _.defaults(object, [sources])
      • _.defaultsDeep(object, [sources])
      • _.findKey(object, [predicate=_.identity])
      • _.findLastKey(object, [predicate=_.identity])
      • _.forIn(object, [iteratee=_.identity])
      • _.forInRight(object, [iteratee=_.identity])
      • _.forOwn(object, [iteratee=_.identity])
      • _.forOwnRight(object, [iteratee=_.identity])
      • _.functions(object)
      • _.functionsIn(object)
      • _.get(object, path, [defaultValue])
      • _.has(object, path)
      • _.hasIn(object, path)
      • _.invert(object)
      • _.invertBy(object, [iteratee=_.identity])
      • _.invoke(object, path, [args])
      • _.keys(object)
      • _.keysIn(object)
      • _.mapKeys(object, [iteratee=_.identity])
      • _.mapValues(object, [iteratee=_.identity])
      • _.merge(object, [sources])
      • _.mergeWith(object, sources, customizer)
      • _.omit(object, [paths])
      • _.omitBy(object, [predicate=_.identity])
      • _.pick(object, [paths])
      • _.pickBy(object, [predicate=_.identity])
      • _.result(object, path, [defaultValue])
      • _.set(object, path, value)
      • _.setWith(object, path, value, [customizer])
      • _.toPairs(object)
      • _.toPairsIn(object)
      • _.transform
      • _.unset(object, path)
      • _.update(object, path, updater)
      • _.updateWith(object, path, updater, [customizer])
      • _.values(object)
      • _.valuesIn(object)
    • “Seq” Methods
      • _(value)
      • _.chain(value)
      • _.tap(value, interceptor)
      • _.thru(value, interceptor)
      • _.prototype[Symbol.iterator]()
      • _.prototype.at([paths])
      • _.prototype.chain()
      • _.prototype.commit()
      • _.prototype.next()
      • _.prototype.plant(value)
      • _.prototype.reverse()
      • _.prototype.value()
    • “String” Methods
      • _.camelCase([string=''])
      • _.capitalize([string=''])
      • _.deburr([string=''])
      • _.endsWith
      • _.escape([string=''])
      • _.escapeRegExp([string=''])
      • _.kebabCase([string=''])
      • _.lowerCase([string=''])
      • _.lowerFirst([string=''])
      • _.pad([string=''], [length=0], [chars=' '])
      • _.padEnd([string=''], [length=0], [chars=' '])
      • _.padStart
      • _.parseInt(string, [radix=10])
      • _.repeat([string=''], [n=1])
      • _.replace([string=''], pattern, replacement)
      • _.snakeCase([string=''])
      • _.split([string=''], separator, [limit])
      • _.startCase([string=''])
      • _.startsWith([string=''], [target], [position=0])
      • _.template([string=''], [options={}])
      • _.toLower([string=''])
      • _.toUpper([string=''])
      • _.trim([string=''], [chars=whitespace])
      • _.trimEnd([string=''], [chars=whitespace])
      • _.trimStart([string=''], [chars=whitespace])
      • _.truncate([string=''], [options={}])
      • _.unescape([string=''])
      • _.upperCase([string=''])
      • _.upperFirst([string=''])
      • _.words([string=''], [pattern])
    • “Util” Methods
      • _.attempt(func, [args])
      • _.bindAll(object, methodNames)
      • _.cond(pairs)
      • _.conforms(source)
      • _.constant(value)
      • _.defaultTo(value, defaultValue)
      • _.flow([funcs])
      • _.flowRight([funcs])
      • _.identity(value)
      • _.iteratee([func=_.identity])
      • _.matches(source)
      • _.matchesProperty(path, srcValue)
      • _.method(path, [args])
      • _.methodOf(object, [args])
      • _.mixin([object=lodash], source, [options={}])
      • _.noConflict()
      • _.noop()
      • _.nthArg([n=0])
      • _.over([iteratees=[_.identity]])
      • _.overEvery([predicates=[_.identity]])
      • _.overSome([predicates=[_.identity]])
      • _.property(path)
      • _.propertyOf(object)
      • _.range([start=0], end, [step=1])
      • _.rangeRight([start=0], end, [step=1])
      • _.runInContext([context=root])
      • _.stubArray()
      • _.stubFalse()
      • _.stubObject()
      • _.stubString()
      • _.stubTrue()
      • _.times(n, [iteratee=_.identity])
      • _.toPath(value)
      • _.uniqueId([prefix=''])
    • Properties
    • Methods
    暂无相关搜索结果！

      本文档使用 BookStack 构建

      展开/收起文章目录

      分享，让知识传承更久远

      文章二维码

      手机扫一扫，轻松掌上读

      文档下载

      • 普通下载
      • 下载码下载(免登录无限下载)
      你与大神的距离，只差一个APP
      APP下载
      请下载您需要的格式的文档，随时随地，享受汲取知识的乐趣！
      PDF文档 EPUB文档 MOBI文档
      温馨提示 每天每在网站阅读学习一分钟时长可下载一本电子书，每天连续签到可增加阅读时长
      下载码方式下载：免费、免登录、无限制。 免费获取下载码

      微信小程序阅读

      BookChat 微信小程序阅读
      您与他人的薪资差距，只差一个随时随地学习的小程序

      书签列表

        阅读记录

        阅读进度: 0.00% ( 0/0 ) 重置阅读进度