Перевод слова "Undefined" с английского на русский онлайн. Перевод слов, фраз и предложений с высокой точностью. Перевод по фото, возможность переводить целые тексты, документы и …

1 day ago · : not defined: such as a : not clearly or precisely shown, described, or limited undefined rules undefined powers a vague, undefined feeling of dread

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Jun 5, 2026 · В JavaScript undefined представляет собой одно из примитивных значений и используется для обозначения ситуации, когда переменной не было присвоено значение.

UNDEFINED definition: 1. not clearly described, stated, or known: 2. not having been given a definition (= a statement…. Learn more.

Jan 10, 2026 · You can use undefined and the strict equality and inequality operators to determine whether a variable has a value. In the following code, the variable x is not initialized, and the if …

Sep 7, 2025 · The meaning of undefined with an overview, related terms, and examples from programming. Understand how undefined variables can lead to common error messages.

If you are interested in knowing whether the variable hasn't been declared or has the value undefined, then use the typeof operator, which is guaranteed to return a string:

2．JavaScript语言中特殊的原始数据类型Undefined，该数据类型只有一个值“undefined”，与另一个特殊原始数据类型NULL在不同的场景下有相似的行为。 (上文中“Undefined”指数据类型，“undefined”指 …

Aug 23, 2023 · We can say null is like loading a webpage and just getting a blank screen, but undefined is a '404 not found' error. The two keywords do have some common traits though.