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SyntaxError: missing : after property id

Error type


What went wrong?

When creating objects with the object initializer syntax, a colon (:) separates keys and values for the object's properties.

var obj = { propertyKey: 'value' };


Colons vs. equal signs

This code fails, as the equal sign can't be used this way in this object initializer syntax.

var obj = { propertyKey = 'value' };
// SyntaxError: missing : after property id

Correct would be to use a colon, or to use square brackets to assign a new property after the object has been created already.

var obj = { propertyKey: 'value' };

// or alternatively

var obj = { };
obj['propertyKey'] = 'value';

Empy properties

You can't create empty properties like this:

var obj = { propertyKey; };
// SyntaxError: missing : after property id

If you need to define a property without a value, you might use null as a value.

var obj = { propertyKey: null };

Computed properties

If you create a property key from an expression, you need to use square brackets. Otherwise the property name can't be computed:

var obj = { 'b'+'ar': 'foo' };
// SyntaxError: missing : after property id

Put the expression in brackets []:

var obj = { ['b'+'ar']: 'foo' };

See also

Tag del documento e collaboratori

 Hanno collaborato alla realizzazione di questa pagina: fscholz
 Ultima modifica di: fscholz,