Child booster seat with a height-adjustable armrest

A child booster seat, comprising:

• a seat base;
• an armrest support coupled to said seat base and formed with an installation space that opens upward, said armrest support having a wall confronting said installation space and formed with a plurality of restraining parts located at different heights of said armrest support;
• and
• an armrest assembly including
• a latching component including a tongue board that extends into said installation space and that is movable vertically within said installation space, and a stop piece that projects from said tongue board for engaging selectively said restraining parts, and
• an armrest component coupled to said tongue board and vertically co-movable with said tongue board relative to said armrest support, said armrest component being supported at a selected height of said armrest support when said stop piece engages one of said restraining parts;
• wherein said tongue board is operable to move said stop piece relative to said armrest component for disengaging said restraining parts and permitting height adjustment of said armrest assembly relative to said armrest support.