1、 A common mistake among novice programmers is forgetting to assign a value to a variable, thus setting the scene for glitches, errors, or unanticipated results. Various programming languages handle "undefined" differently, often tied to their typical paradigms and conventions, thus a nuanced understanding of the particular language at play is required. For instance, when it’s declared but hasn't been assigned a value, it's often "undefined" by default， Primitive types such as "string," "number," and "boolean" are co-domains of functions.
2、 This is why undefined values serve as red flags and demand immediate attention， It may speak to the compelling allure of the mysterious, the unresolved, the areas of knowledge not yet charted. In sum, "undefined", whether viewed through the lens of computer programming or in its more abstract general usage, stands testament to the unpredictable, the unanticipated, and the as-yet-unresolved that loom ever present in both human endeavor and intellectual pursuit.
3、 In JavaScript, recognizing the significance of undefined isn't to be underestimated， In TypeScript, in contrast to JavaScript, a specific type, "undefined," exists.In computer programming contexts, "undefined" possesses a particular and potent significance， A variable might be undefined in several scenarios. Often, when a program behaves unpredictably or performs in ways contrary to initial expectations, the culprit is an undefined variable， In literature, the term "undefined" has a much broader, metaphorically rich meaning, often symbolising the unknowable, indeterminate, or endlessly variable nature of something.
