Javascript赋值变量if为nil

Javascript assign variable if nil?

本文关键字：nil if 变量 赋值 Javascript      更新时间：2023-09-26

是否有一些速记在Javascript中分配一个变量，如果它的计算结果为false?

在ruby中我可以这样做:

foo |= "bar"

如果foo求值为false，则将"bar"赋值给foo就像这样:(使用那个|=运算符)

var cars_by_brand_and_color = {};
for (var car in parking_lot) {
   // add a brand if it doesn't exist yet;
   // cars_by_brand_and_color['chevrolet'] = {};
   cars_by_brand_and_color[car['brand']] |= {};
   // and add that color to the brand if it doesn't exist yet;
   // cars_by_brand_and_color['chevrolet']['grey'] |= {}; 
   cars_by_brand_and_color[car['brand']][car['color']] |= {};
   // now let's add that car; 
   // cars_by_brand_and_color['chevrolet']['grey']['BDB-565'] = 'Mr. Smith';
   cars_by_brand_and_color[car['brand']][car['color']][car['lisence_plate']] = car['owner']
};

当然，JS语法是

var toAssign = mayBeNull || {};
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