React: Can I check if a state exists before rendering it
Sure, use a ternary:
render() { return ( this.state.name ? <NavItem>{this.state.name}</NavItem> : null );}or even shorter
render() { return ( this.state.name && <NavItem>{this.state.name}</NavItem> );}
Sure you can:
let userNavItemif (this.state.name !== undefined) { userNavItem = <NavItem eventKey={4} href="#">{this.state.name}</NavItem>} else { userNavItem = null}Now you can use userNavItem on your navbar component, and it will render only if this.state.name is defined.
In React, you can check if a state exists before push
checkedProduct=(prop)=>{ var checkIfExist = this.state.checkedProduct.filter((product)=>{ return product===prop }) if(checkIfExist.length>0){ var checkIfExist = this.state.checkedProduct.filter((product)=>{ return product!==prop }) this.setState({ checkedProduct:checkIfExist }) }else{ this.setState({ checkedProduct: this.state.checkedProduct.concat(prop) }) }}