Detailed explanation of usage examples of the reduce() method that comes with JavaScript

1. Method description, Array's reduce() applies a function to [x1, x2, x3...] of this Array. This function must receive two parameters, and reduce() continues the result with the sequence. The next element is cumulatively calculated, and the effect is:

[x1, x2, x3, x4].reduce(f) = f(f(f(x1, x2), x3), x4)

2. Usage example

'use strict';
function string2int(s){
if(!s){
alert('the params empty');
return;
}
if(s.length===1){
return s*1;
}
var arr = [];
for(var i=0; i<s.length; i++){
arr.push(s.substr(i, 1)*1);
}
return arr.reduce(function(x, y){
return x*10 + y;
});
}
// 测试:
if (string2int(&#39;0&#39;) === 0 && string2int(&#39;12345&#39;) === 12345 && string2int(&#39;12300&#39;) === 12300) {
if (string2int.toString().indexOf(&#39;parseInt&#39;) !== -1) {
alert(&#39;请勿使用parseInt()!&#39;);
} else if (string2int.toString().indexOf(&#39;Number&#39;) !== -1) {
alert(&#39;请勿使用Number()!&#39;);
} else {
alert(&#39;测试通过!&#39;);
}
}
else {
alert(&#39;测试失败!&#39;);
}

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