temp.js

selectItem (item) {
    if (!this.multiple) {
      this.inputValue = item
    } else {
      if (this.inputValue === null) {
        this.inputValue = [item]
      } else {
        const i = this.inputValue.findIndex(i => this.getValue(i) === this.getValue(item))

        if (i !== -1) {
          this.inputValue.splice(i, 1)
        } else {
          this.inputValue.push(item)
        }
      }
    }

    if (this.autocomplete) {
      this.$nextTick(() => {
        this.searchValue = null
        this.$refs.input.focus()
      })
    }
  }
},
  
// Refactor #1  
//
// Shift the reading of the eyes to a quicker vertical scan.
// No big "else". Nested small "if/else" blocks that are only 1 level deep
// are fine. Try to see if it's more readable as a ternary (not always though).
// But anymore nesting may mean you need to call a function or apply some other
// refactor. 
  
selectItem (item) {
    if (!this.multiple) {
      this.inputValue = item
    }
  
    if (this.multiple && this.inputValue === null) {
      this.inputValue = [item]       
    }
  
    if (this.multiple && this.inputValue !== null) {
      const i = this.inputValue.findIndex(i => this.getValue(i) === this.getValue(item))

      if (i !== -1) {
        this.inputValue.splice(i, 1)
      } else {
        this.inputValue.push(item)
      }      
    }

    if (this.autocomplete) {
      this.$nextTick(() => {
        this.searchValue = null
        this.$refs.input.focus()
      })
    }
  }
},  
  
// Refactor #2
// 
// Let's move complexity to a method. But be balanced about it.
// The Ruby on Rails folk will try to tell you that you need to refactor
// away all conditions and stuff, but you end up with method explosion
// (which means you have to jump around a lot to fully understand what's happening).
  
selectItem (item) {
    if (!this.multiple) this.inputValue = item
    
    if (this.multiple) this.selectItemMultiple(item)
    
    if (this.autocomplete) {
      this.$nextTick(() => {
        this.searchValue = null
        this.$refs.input.focus()
      })
    }
  }
},  
    
// Refactor #3
// 
// We could see if reducing vertical space further helps or not.
// A ternary can sometimes help. Here is where coding becomes artform.
// You make judgement calls. Use a ternary, or do I lose some context
// of what I'm doing? Return early, or is the last left over code out of context?
  
selectItem (item) {
    this.multiple ? this.selectItemMultiple(item) : this.inputValue = item

    if (this.autocomplete) {
      this.$nextTick(() => {
        this.searchValue = null
        this.$refs.input.focus()
      })
    }
  }
},