util.format(format[, ...args])

• format <string> 类似 printf 的格式字符串。

  \format <string> A printf-like format string.

util.format() 方法使用第一个参数作为类似 printf 的格式字符串(其可以包含零个或多个格式说明符)来返回格式化的字符串。每个说明符都替换为来自相应参数的转换后的值。支持的说明符有:

\The util.format() method returns a formatted string using the first argument as a printf-like format string which can contain zero or more format specifiers. Each specifier is replaced with the converted value from the corresponding argument. Supported specifiers are:

• %s:String 将用于转换除 BigInt、Object 和 -0 之外的所有值。BigInt 值将用 n 表示,而没有用户定义的 toString 函数和 Symbol.toPrimitive 函数的对象将使用带有选项 { depth: 0, colors: false, compact: 3 } 的 util.inspect() 进行检查。

  \%s: String will be used to convert all values except BigInt, Object and -0. BigInt values will be represented with an n and Objects that have neither a user defined toString function nor Symbol.toPrimitive function are inspected using util.inspect() with options { depth: 0, colors: false, compact: 3 }.

• %d:Number 将用于转换除 BigInt 和 Symbol 之外的所有值。

  \%d: Number will be used to convert all values except BigInt and Symbol.

• %i:parseInt(value, 10) 用于除 BigInt 和 Symbol 之外的所有值。

  \%i: parseInt(value, 10) is used for all values except BigInt and Symbol.

• %f:parseFloat(value) 用于除 Symbol 之外的所有值。

  \%f: parseFloat(value) is used for all values expect Symbol.

• %j:JSON.如果参数包含循环引用,则替换为字符串 '[Circular]'。

  \%j: JSON. Replaced with the string '[Circular]' if the argument contains circular references.

• %o:Object。具有通用 JavaScript 对象格式的对象的字符串表示形式。类似于具有选项 { showHidden: true, showProxy: true } 的 util.inspect()。这将显示完整的对象,包括不可枚举的属性和代理。

  \%o: Object. A string representation of an object with generic JavaScript object formatting. Similar to util.inspect() with options { showHidden: true, showProxy: true }. This will show the full object including non-enumerable properties and proxies.

• %O:Object。具有通用 JavaScript 对象格式的对象的字符串表示形式。类似于没有选项的 util.inspect()。这将显示完整的对象,但不包括不可枚举的属性和代理。

  \%O: Object. A string representation of an object with generic JavaScript object formatting. Similar to util.inspect() without options. This will show the full object not including non-enumerable properties and proxies.

• %c:CSS。此说明符被忽略,将跳过任何传入的 CSS。

  \%c: CSS. This specifier is ignored and will skip any CSS passed in.

• %%:单个百分号 ('%')。这不消费参数。

  \%%: single percent sign ('%'). This does not consume an argument.

• 返回:<string> 格式化的字符串

  \Returns: <string> The formatted string

如果说明符没有相应的参数,则不会替换它:

\If a specifier does not have a corresponding argument, it is not replaced:

util.format('%s:%s', 'foo');
// Returns: 'foo:%s' 拷贝

如果其类型不是 string,则不属于格式字符串的值将使用 util.inspect() 进行格式化。

\Values that are not part of the format string are formatted using util.inspect() if their type is not string.

如果传给 util.format() 方法的参数多于说明符的数量,则额外的参数将以空格分隔串联到返回的字符串:

\If there are more arguments passed to the util.format() method than the number of specifiers, the extra arguments are concatenated to the returned string, separated by spaces:

util.format('%s:%s', 'foo', 'bar', 'baz');
// Returns: 'foo:bar baz' 拷贝

如果第一个参数不包含有效的格式说明符,则 util.format() 返回以空格分隔的所有参数的串联的字符串:

\If the first argument does not contain a valid format specifier, util.format() returns a string that is the concatenation of all arguments separated by spaces:

util.format(1, 2, 3);
// Returns: '1 2 3' 拷贝

如果只有一个参数传给 util.format(),则它会按原样返回,不进行任何格式化:

\If only one argument is passed to util.format(), it is returned as it is without any formatting:

util.format('%% %s');
// Returns: '%% %s' 拷贝

util.format() 是同步的方法,旨在用作调试工具。某些输入值可能会产生显着的性能开销,从而阻塞事件循环。小心使用此函数,切勿在热代码路径中使用。

\util.format() is a synchronous method that is intended as a debugging tool. Some input values can have a significant performance overhead that can block the event loop. Use this function with care and never in a hot code path.