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Interpolation

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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

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