Home > Article > Backend Development > How to Iterate Through Parallel Arrays in HTML/Template using the `index` Function?
Many development scenarios involve working with parallel arrays, where two or more arrays have the same size and their elements should be accessed in a synchronized manner. Understanding how to iterate through these parallel arrays becomes crucial in such situations.
Question:
How can index within a range block be used to iterate through parallel arrays in HTML/Template?
Failed Attempt:
This code fails to achieve the desired result:
{{range $i, $e := .First}}$e - {{index .Second $i}}{{end}}
Solution:
The key to succeeding here is leveraging the index function, a predefined global template function in HTML/Template. It allows indexing of the first argument by subsequent arguments.
index Returns the result of indexing its first argument by the following arguments. Thus index x 1 2 3 is, in Go syntax, x[1][2][3]. Each indexed item must be a map, slice, or array.
The initial code fails because it does not account for the reassignment of dot within the range block. To access the original dot, we can utilize another predefined template function:
When execution begins, $ is set to the data argument passed to Execute, that is, to the starting value of dot.
An improved version of the code becomes:
{{range $i, $e := .First}}$e - {{index $.Second $i}}{{end}}
Alternative Approach:
Consider a cleaner approach by defining a custom template function called zip. This function takes multiple slices as input and generates a slice of pairs, one for each corresponding element in the input slices. It can then be used in the template to simplify the iteration process.
The above is the detailed content of How to Iterate Through Parallel Arrays in HTML/Template using the `index` Function?. For more information, please follow other related articles on the PHP Chinese website!