interpolation.md

Interpolation

Interpolation

Interpolation is one of the most used functionalities in I18N. It enables you to integrate dynamic values into your translations.

Per default, interpolation values get escaped to save you from possible xss attacks.

If the interpolation functionality provided doesn't suit you, you can use i18next-sprintf-postProcessor for sprintf supported interpolation.

Basic

Interpolation is one of the most used functionalities in I18N.

Keys

Keys, by default, are strings surrounded by curly brackets:

{
    "key": "{{what}} is {{how}}"
}

Sample

i18next.t('key', { what: 'i18next', how: 'great' });
// -> "i18next is great"

Working with data models

You can also pass entire data models as a value for interpolation.

Keys

{
    "key": "I am {{author.name}}"
}

Sample

const author = { 
    name: 'Jan',
    github: 'jamuhl'
};
i18next.t('key', { author });
// -> "I am Jan"

Unescape

Per default the values get escaped to save you from possible xss attacks. You can toggle escaping off, by either putting - before the key, or set the escapeValue option to false when requesting a translation.

Keys

{
    "keyEscaped": "no danger {{myVar}}",
    "keyUnescaped": "dangerous {{- myVar}}"
}

Sample

i18next.t('keyEscaped', { myVar: '<img />' });
// -> "no danger &lt;img &#x2F;&gt;"

i18next.t('keyUnescaped', { myVar: '<img />' });
// -> "dangerous <img />"

i18next.t('keyEscaped', { myVar: '<img />', interpolation: { escapeValue: false } });
// -> "no danger <img />" (obviously could be dangerous)

Warning: If you toggle escaping off, you should escape any user input yourself!

Additional options

Prefix/Suffix for interpolation and other options can be overridden in the init options or by passing additional options to the t function:

i18next.init({
    interpolation: { ... }
});

i18next.t('key', {
    interpolation: { ... }
});

option	default	description
escape	function	escape function function escape(str) { return str; }
escapeValue	true	escapes passed in values to avoid xss injection
useRawValueToEscape	false	If true, then value passed into escape function is not casted to string, use with custom escape function that does its own type check
prefix	"{{"	prefix for interpolation
suffix	"}}"	suffix for interpolation

While there are a lot of options going with the defaults should get you covered.

All interpolation options

option	default	description
format	noop function	format function see formatting for details
formatSeparator	","	used to separate format from interpolation value
escape	function	escape function function escape(str) { return str; }
escapeValue	true	escape passed in values to avoid xss injection
useRawValueToEscape	false	If true, then value passed into escape function is not casted to string, use with custom escape function that does its own type check
prefix	"{{"	prefix for interpolation
suffix	"}}"	suffix for interpolation
prefixEscaped	undefined	escaped prefix for interpolation (regexSafe)
suffixEscaped	undefined	escaped suffix for interpolation (regexSafe)
unescapeSuffix	undefined	suffix to unescaped mode
unescapePrefix	"-"	prefix to unescaped mode
nestingPrefix	"$t("	prefix for nesting
nestingSuffix	")"	suffix for nesting
nestingPrefixEscaped	undefined	escaped prefix for nesting (regexSafe)
nestingSuffixEscaped	undefined	escaped suffix for nesting (regexSafe)
defaultVariables	undefined	global variables to use in interpolation replacements defaultVariables: { key: "value" }
maxReplaces	1000	after how many interpolation runs to break out before throwing a stack overflow