x==y returns true
x===y returns false
(x < 10 && y > 1) returns true
|| or(x==5 || y==5) returns false
! not!(x==y) returns true
A string is most often text, for example "Hello World!". To stick two or more string variables together, use the + operator.
在文字當中使用的比較多,舉例來說“Hello World!”要將兩個或多個字符串變量銜接在一起的話就得使用 + 符號
txt1="What a very" txt2="nice day!" txt3=txt1+txt2
The variable txt3 now contains "What a verynice day!".
txt3變量現在包含“What a verynice day!”(把1和2銜接起來了)
To add a space between two string variables, insert a space into the expression, OR in one of the strings.
要給兩個字符串變量中間添加空格就得在表達式裡插入空格,或在其中的一個加上(空格)
txt1="What a very" txt2="nice day!" txt3=txt1+" "+txt2
or
txt1="What a very " txt2="nice day!" txt3=txt1+txt2
The variable txt3 now contains "What a very nice day!".
現在變量txt3為“What a very nice day!”
JavaScript also contains a conditional operator that assigns a value to a variable based on some condition.
JS有根據條件不同給變量不同值的條件運算符
variablename=(condition)?value1:value2
greeting=(visitor=="PRES")?"Dear President ":"Dear "
If the variable visitor is equal to PRES, then put the string "Dear President " in the variable named greeting. If the variable visitor is not equal to PRES, then put the string "Dear " into the variable named greeting.
如果變量visitor的值等於PRES那麼greeting的值就為"Dear President "。如果不為PRES那麼greeting的值就為"Dear"